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A 



TREATISE ON ACOUSTICS 



IN CONNECTION WITH 



VENTILATION; 



-A-i^ ^ooouisrrr 



Modem and Ancient Methods of Heating and Yentilation. 



By ALEXANDER SAELTZEE, 

ABCHITECT. — '^'--»^ 

:r n V) 

— -^ — ., j.o.2Sn^^ 

NEW YORK: 

D. VAN NOSTRAND, PUBLISHER, 

23 UcBKAt Street and 27 Wabrek Street. 

li72. 



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Entered according to act of Congress, in the year 1872, by 

D. VAN NOSTRAND, 
in the Office of the librarian of Congress at Washington, 



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PREFACE. 



It appears to me necessary to make a few remarks 
in advance, as I am anxious the book which I herewith 
lay before the public, should at least receive a friendly 
acknowledgment of the many days' and even months' 
time of my strictest observation. The title of this book 
embraces much that is of great importance, especially 
on the subject of acoustics, as the problem introduced 
in it which I have endeavored to explain and to vindi- 
cate, will prove. 

It is the first attempt, in its peculiar nature, ever 
presented to the public ; at least I believe that all the 
former experience upon the subject of acoustics, refer- 
ring to public buildings, may be placed in a secondary 
light, without fear of being considered arrogant. There 
must be a good cause why this proposed theory has 
not been advanced by any other higher professional 
pen previously. And surely the cause is clear, as sci- 
ence in this particular branch is too young, and it is 
only in this nineteenth century that the nature of sound 
has been partially discovered. A large field is still 



4 PKEFACE. 

open ; many obstructions will have to be cleared away, 
and many individuals will have to assist, with manifold 
labor, to concentrate, and confine progressively, the 
harmonious dictates of nature. I have been often 
placed in a very unpleasant position, in the construc- 
tion of public buildings, where acoustics have formed 
a most important part, and in which the want of knowl- 
edge on sound has caused a feeling of actual discour- 
agement to proceed, and I have no doubt many archi- 
tects have found themselves in the same predicament. 
This new theory will obviate this uncertainty, as well 
as confine and regulate sound in its proper course and 
action, and in being found correct will justify me for 
the expression of my inmost conviction. 

A. SAELTZER, 

ArchiteoL 

New Yobk, 

49 WaU street. 



ACOUSTICS. 



Ant practical fact relating to science can never be 
traced, except througli the thorough knowledge of 
nature, and our progress in this sphere will always be 
either checked or advanced accordingly. 

This new and important discovery will undoubtedly 
prove these assertions, and will produce a plain and 
striking example, which, I hope, w^ill assist all future 
arrangements and do away with all the existing evils 
in public halls or buildings, at least as much so as 
possible, and the changes will be precisely in propor- 
tion to the application of the new remedy to the exist- 
ing mismanagement of form, proportion, and construc- 
tion heterogene to nature. 

Sound receives its vitality or its life through the air, 
and, without air sound loses it and becomes extinct. 

Before I proceed to explain the new discovery, I will 
first introduce a number of facts showing the relative 
attributes of sound in connection with air, from the 
best authorities, not alone as being interesting, but as 
a necessity, for the remedy which I propose for build- 
ings of all classes where sound has proved a failure. 

" The intensity of sound depends on the density of 
" the air in which sound is generated, and not on that 
" of the air in which it is heard. A feeble sound 



6 ACOUSTICS, 

* becomes instantly louder as soon as the air becomes 
^ more dense. So you will always find on great eleva- 
' tions in the atmosphere the sound sensibly diminished 

in loudness. If two cannon are equally charged and 
' one fired at the top of a high mountain and the other 

* in a valley, the one fired below in the heavy air may 
^ be heard above, while the one fired in the higher air 
' will not be heard below ; owing to its origin, the 
^ sound generated in the denser air is louder than that 
' generated in the rarer. Peals of thunder are unable 
^ to penetrate the air to a distance commensurate with 
^ their intensity, on account of the non-homogeneous 

* character of the atmosphere which accompanies 
' them ; from the same cause battles have raged and 
' have been lost within a short distance of the reserves 
' of the defeated army while they were waiting for the 
' sound of artillery to call them to the scene of action." 

Science teaches us, that whenever a shock or pres^ 
sure of any sort is suddenly applied to any material of 
any nature, whether metal, wood, gas, water, air, etc., 
it is immediately affected in all its parts, from the point 
of contact to the whole extent of the material, in dis- 
placing and replacing the particles of a determinate 
volume ; and the velocity of the movement of the par- 
ticles of the mass created by the concussion of shocks 
or pressure depends solely upon the nature of any 
material, upon its elasticity and density ; sound likewise 
causes motions with every particle of the air, and as 
far as the motion reaches, so that each particle with 
regard to that which lies immediately beyond it, is in 



ACOUSTICS, 7 

a progress of rarification during return. " All parts 
which go forward do in their progressive motion strike 
each obstacle they meet in their way ; they are for that 
reason called pulses, and the sensations which are ex- 
cited in the mind by the strokes of these pulses on the 
drum of the ear are called sounds, considered in their 
physical causes are nothing else than the pulses of the 
air." "In order therefore to explain the nature of 
sound I will add the chief properties of these pulses. 
The first is, that they ar^ propagated from the trem- 
bling body all around in a spherical manner. For the 
pulses go and return according to certain directions 
from the parts of the body by whose vibrations they 
are generated ; yet for as much as every impression 
which is made on a fluid is propagated every way 
throughout the fluid, whatever be the direction wherein 
it is made in like manner the pulses must spread and 
dilate so as to form themselves into concentric spheri- 
cal surfaces, or rather shells, whose common centre is 
the place of the soimding body. And hence appears 
the reason why one and the same sound may be heard 
by several persons, though differently situated with 
respect to the sounding body." 

"A second property of the pulses is that they grow 
less and less dense as they recede from the sounding 
body, and in the same proportion with the squares of 
their distances from the body. For whatever be the 
force wherewith the sounding body acts on the first 
spherical shell of air, with the very same force does 
that shell act upon the second, and that again upon 



8 ACOUSTICS. 

the third, and so on continually, so that the force which 
condenses the air in the several shells is given ; conse- 
quently the condensation which it produces in those 
shells must be inversely as the resistance it meets with 
but the resistances are at each shell, and, therefore, 
since they increase continually in the same proportion 
with the squares of their distance from the centre, their 
density must increase in the same manner. By reason 
of their diminution in the densities of the pulses, those 
which are further removed from the sounding body 
make lighter impressions on the drum of the ear than 
those which are less distant, and hence it is that 
sounds grow less and less audible, the further they go 
from the sounding body, and at certain distances be- 
come so weak as not to be heard at all." 

" A third property of the pulses is, that all of them, 
whether denser or rarer, move equally swiftly, so as to 
be carried through equal spaces in equal time. From 
this property it follows that all sounds, whether they 
be loud or low, grave or acute, move equally swiftly ; 
the softest whisper making equal speed with the noise 
of a cannon, or the loudest thunder clap ; and it has 
been found by experiment that sounds move at the rate 
of 1,142 feet in a second of time, or thereabouts, for 
the velocity is not precisely the same in all seasons of 
the year, but is somewhat greater in summer than in 
winter, on account of the heat, which renders the air 
more elastic in proportion to its density than it is in 
the cold winter season." 

Any room, hall, church, etc., or any space enclosed 



ACOUSTICS. (9 

by walls, ceiling and floor, compresses the air in a state 
of greater density compared with the atmospheric air, 
and consequently the sound in such places should 
always be more distinct than the sound in the open 
air in proportion to a determinate volume, a fact which 
is of importance and which has been demonstrated 
sufficiently. Now, if we take even a one-sided view of 
the case, which represents itself conclusively, this ad- 
vantage of great density alone would be sufficient to 
assist sound for any practical purpose, but this is not 
the case, and why ? The density of the air in those 
rooms is generally in an unhealthy state, heterogeneous 
to the nature of sound, and even to health itself, from 
various causes which I will explain more in detail. 

It has been mentioned before that the air is strongly 
affected by cold, heat, dampness, gases, etc., and in 
proportion as the air varies from the pure state to too 
much dampness, too much cold, etc., the vitality of the 
sound is more or less affected. Next follows the mix- 
ture of different strata of air, which will each affect the 
sound more or less in its propelling power, the densi^ 
ties of the strata of air differing ; this difference in the 
state of air is found also in empty rooms. 

In halls, churches, theatres, eto., crowded with 
people, the density of the air increases bj^ the bodies 
still more ; but this increase of density is balanced 
somewhat by the loss of reflection. 

We often find theatres or churches filled with gloomy 
air before they are occupied ; and if the air exhaled by 
thousands of people as3embl8d be added, it causes a 



10 ACOUSTICS. 

perfect revolution of different strata of air, even more 
adverse to the development of intelligible sound. The 
bad air which is created by exhalation is heavier 
than all the rest, except atmospheric air, and natu- 
rally sinks to the lower portion of the hall and dif- 
fuses itself, the more so where there are galleries ; and 
precisely in proportion as this bad air increases in 
volume the sound becomes less and less, in a theatre it 
being noticeable first in the pit, then in the first gallery, 
and so on upwards ; and hence you will often notice 
that in the upper galleries, or upper parts of the house 
the hearing is more distinct. Bad air, it is true, be- 
comes much more dense, but the substances of this 
air are poison to the vitality of the sound, as well as 
to health, mind, lungs, and voice, and this proves that 
sound can only carry out its function when well sup- 
plied with healthy and congenial air. If you notice 
the changes of sound in crowded houses, and follow its 
diminishing state of existence, you will first find its 
nature often in tolerably good humor, then it becomes 
delirious, and is placed in a most uncomfortable posi- 
tion, not knowing which way to turn ; poison on all 
sides, ever anxious to do its duty, full of its natural 
vitality, it becomes disheartened, leaves first its battle 
field, the pit, next the first gallery, then the second, 
third, etc., and at last, exhausted, looks up as high as 
possible to gain rest in the strata of warmer and more 
flexible air, air more congenial to its nature, which is 
always found at the highest point. 
- This is a true picture of the condition of sound in 



ACOUSTICS. 11 

theatres, etc., where there is not a proper ventilation ; 
and why has ventilation not been applied for this pur- 
pose of propagating sound? Because ventilation is 
comparatively new, and is hardly, or very little under- 
stood in its proper light ; in its effect upon sound in 
buildings no such idea has as yet become known, and 
it is strange, but nevertheless true, that there cannot 
be found a book on acoustics, that I am aware of, in 
which ventilation is mentioned in connection with it. 
Ventilation here forms the most important part in the 
consistency of nature, and if only properly and scien- 
tifically executed, the greatest point is gained ; form, 
however, and construction, proportion, and size, ma- 
terials, and even art has to be introduced to form a 
combination or amalgamation to gain success, and to 
be truthful to the dictates of nature, which never 
deceives. 

Architects hitherto have considered form and ma- 
terial and size the only prominent features to assist 
sound, and hence the uncertainty of the results. The 
prevailing opinion is also established, that vaulted an 1 
curved roofs and ceilings act as mirrors upon sound. 
In one of the cathedrals in Sicily the Confessional was 
so placed that the whispers of the penitents were re- 
flected by the curved roof, and brought to a focus at a 
distant part of the edifice. There is also a whisper- 
ing gallery in St. Paul's Cathedral in London, a moot 
astounding phenomenon, a mere accident not calcu- 
lated upon originally. Now, if we rest upon the as- 
sumption that a pure air, genial to sound, guides the 



12 ACOUSTICS. 

path of sound, this mystery is solved at once. I will 
here explain how such a singular case may be effected. 
The St. Paul's Cathedral, in London, and the Cathe- 
dral in Sicily are large edifices, with exterior as well as 
interior walls of solid masonry ; they are only used on 
particular occasions, and ventilation is entirely foreign 
to them, and the consequence is that the air in them is 
almost like cellar air, damp and heavy, inclined to stop 
the pulses created by sound, in consequence of which 
the lower strata of air are repulsive to sound. AH the 
warmer and more elastic air at the highest point in 
such buildings is always created by a draft of air from 
doors and windows, and somewhat vitalized by the 
sun reflecting its warmth through the windows, no 
matter what the colors of the glass may be ; although 
some colors have the tendency to draw heat more than 
others. The air introduced into these buildings by 
draft from the outer atmosphere is often lighter and of 
better quality than the inner air, and rises according 
to its flexibility to the higher places under the ceiling, 
and a somewhat continued draft will certainly have the 
tendency to clarify the interior air of a dome, for in- 
stance, like that of St. Paul's Cathedral, and it will 
always be a focus of attraction, especially where there 
is much light introduced, even without escape of air. 
Now let us trace our steps to the Confessional, and fol- 
low the voice from the pastor's lips, and his position. 

The pastor is situated in the Confessional, a box or 
tube in form. In this tubo the air is more dense than 
the surrounding air, and it gains more vigor, the 



ACOUSTICS. 13 

pastor's head being about 5 feet or sometimes more 
above the level of the church floor, his voice strikes 
above the lower strata of damp air, which are the 
heaviest ; and, as the strata become lighter and more 
elastic according to their elevation, it is natural that 
the sound rises immediately to the higher strata and 
continues under the ceiling to a certain distance, till it 
strikes a volume of air which has been revolutionized 
by draft from the outside or to a locality where those 
influences are mostly concentrated, and hence the 
downward movement of the sound to the lower part of 
the building and to a distinct place ; in fact the sound 
marches swiftly beyond the heavy volumes of air con- 
tained in the body of the church, and seeks a path 
downwards as soon as nature assists. Now, some 
might take it for granted that this same effect might 
be gained by placing the Confessional in another situa- 
tion, and it would likely prove a failure ; but this vrould 
be no criterion, no proof whatever, against the theory 
advanced, because light may be more effective on one 
side than on the other, the draft of air also may be 
more on one side, than on the other ; much also will 
depend on the situation of the building itself. 

The theory advanced will also aboUsh sound-boards 
over pulpits ; how is it possible that a sound-board, 
even 8 or 10 feet square or circular, should cause the 
sound to descend to the lower strata of air full of 
poison ; never will its nature consent to such unreason- 
able demands ; no, it will, like a bird leaving its open 
cage to seek its liberty, pass the outlines of the sound- 



14 ACOUSTICS. 

irig-board to rise to a higher sphere, in the very reverse 
direction to that desired. Forget not that sonnd is of a 
nobler character than generally supposed ; its require- 
ments are a distinguished treatment, and it will resist 
every infringement upon its dignity, and hence, not 
only through science, but even art, is an approach for 
hearing possible. 

In my own experience at several of the public build- 
ings in this city which were erected under my superin- 
tendence, for example the old Academy of Music in Four- 
teenth street, a building of more capacity than any of 
modem times, sound proved to be excellent. In another 
public building, where the ventilating apparatus was, 
in the hurry of opening the building for the first night, 
neglected, in fact entirely forgotten, all the ingress and 
egress of air was hermetically closed; the house was 
crowded to excess, and the heat and bad air accumu- 
lated so much that the sound became perfectly unintel- 
ligible. I noticed the effect, and in half an hour after 
the apparatus was in action, the sound became per- 
fectly clear and distinct. 

Many illustrations and examples to prove the bad 
state of air existing in most of our public buildings 
might be introduced, and its effect upon sound, but I 
think it better to pass over them ; however, I will take 
the liberty of saying a few words, and will point out 
the causes why the Hall of Eepresentatives and the 
Senate Chamber in the Capitol at Washington are any- 
thing but desirable for the purpose of good hearing. 
Each of these halls is of an oblong form, the galleries 



AcoasTics. 15 

project from the enclosing walls inwardly on all sides, 
and are of considerable depth enclosed underneath. 
Each hall has a large skylight corresponding with the 
form of the hall ; in such the light is not direct, but 
only a reflected light, and in gloomy days hardly sufli- 
cient, rather dull ; the Speaker's desk is placed on the 
longitudinal side of the hall, and the lower seats radi- 
ating in a circle towards the Speaker's desk. In the 
lower part of the halls enclosed by the galleries, the 
contracted space naturally assists sound, the air being 
more condensed; but ventilation is insufficient, and the 
lower columns of air being heavy, the sound rises above 
the galleries to the more open space above. If the 
two halls were calculated to be occupied for only a 
few hours' time, and well ventilated, it might answer 
very well ; but being occupied the whole day and often 
crowded, the quantity of air contained in the whole 
space is insufficient, and as the ceilings are too low 
above the galleries, the strata of air become very of- 
fensive, and with the dim light through the skylights 
you will find those halls anything but pleasant ; that 
the elastic vitality requisite to clear reflection of mind 
and sound is impaired, and that the bodies become 
feverish, nervous and restless, none of the Senators and 
Congressmen will deny. The exclusion of a direct 
light, which always gives life and elasticity to a conge- 
nial air for sound and health, aside from the effect of a 
poisoned air, was a great mistake^ If these halls were 
better ventilated, with the light as it is, they would be 
excellent for fattening purposes, but ruin to the liver. 



16 ACOUSTICS. 

In regard to the form of these halls, I will refer here- 
after. Strong lighted halls will always be best for 
sound, as light is part of ventilation and adds great 
elasticity to the air. 

The sun, our great benefactor, supplies us with heat 
and light ; the whole day long we enjoy this blessing 
direct, and through this influence the night air remains 
healthy. Now imagine a locality like the Senate Cham- 
ber and Hall of Representatives, insufficient in venti- 
lation, insufficient in the quantity of air, and in the 
exclusion all day of direct light ; could the result be 
expected otherwise ? I will introduce here another 
example to prove the correctness of my assertions. 
You will sometimes find theatres, churches, etc., with 
tolerably intelligible sound without much ventilation, 
and how is this possible ? Then mark, in all those 
cases you will find more air than is requisite for 
breathing, and consequently it takes longer time to 
affect the air with poison, or the house is only partly 
filled, a circumstance which assists much ; but to as- 
sist sound by increasing the volume of air more than 
necessary would be an expensive operation, and then 
it would only be one-sided, and would to a certain ex- 
tent put a restriction upon the use of the house. 

This theory will lead to innumerable changes if 
properly followed ; it will infuse fresh air into the lungs, 
and add to health ; it will arouse the stupor of the 
audience, caused by poisoned air ; it will assist elo- 
quence and strength of voice ; it will assist sound 
reasoning, and it will assist to elevate the mind. Will 



ACOUSTICS. 17 

not this theory benefit multitudes of hearers who now, 
in thousands of cases, go home dissatisfied with the 
loss not only of their time, but, with it, the loss of 
knowledge, as it was impossible to hear, and the op- 
portunity for gaining which may never return? A stamp 
will be placed upon future temples of a true character, 
which will allow thousands of people to assemble, 
and afford a more extensive diffusion of knowledge, 
the want of which now is so keenly felt. 

SIZE AND FORM OF PUBLIC HALLS. 

Now I will turn to the details of size, form, ma- 
terials, and art, to show how necessary these attributes 
are to assist sound, even in all its full vigor of life. 
Sound must have no obstacles ; its nature is disturbed 
almost like the sharp edge of a razor; no matter how 
perfect the steel may be its nature is the same, that of 
the most refined kind, the most susceptible of any in- 
harmonious infringement. 

No doubt every reader will admit that a certain ex- 
tent of space is necessary for the diffusion of sound ; 
if the space is too large the sound will exhaust itself at 
a certain distance ; this fact proves itself almost daily. 
Many experiments prove that in theatres the sound 
from a clear speaking voice is distinctly heard to a 
distance of 80 feet in front ; but this is a maximum not 
to be overstepped ; in the direction of 60 feet on each 
side, and in the rear, of 40 or 50 feet. This proportion 
of figures will lead at once to the conclusion that the 



18 ACOUSTICS. 

best form for sound or distinct hearing will confine 
itself to the circle or egg-lines ; the extent, however, of 
distinct sound in buildings, other than theatres, where 
the arrangements of seats and form are different, may * 
even reach the distance of 150 feet in front, on each 
side 80 feet, and 60 feet towards the rear, and even 
more. The first named figures, as I stated before, led 
to a circle with the central point 20 feet from the 
speaker, or to a form approaching an ellipsis. 

The three-quarter circle form has proved itself the 
best so far in a theatre ; but still improvements might 
be made even in this form. The three-quarter circle 
lines near the ends are not calculated to contract the 
sound in its forward march sufficiently, and a funnel- 
like direction of the side lines, starting from the pro- 
scenium in an oblique direction to the right and left, 
inclosing the liaes with a circle, would surely assist the 
force of sound in its forward course ; this arrangement 
would allow many additional seats, would not only 
assist decoration, but even construction and save ex- 
pense. Without doubt the best and most practical 
method to strengthen sound in any building calculated 
for hearing, is to break the same in such a manner as 
to facilitate its natural course from its original starting- 
point toward the hearers, with due regard to the 
natural and reflecting or broken sound, producing dif- 
ferences in time, which would lead to confusion rather 
than strength, and to avoid this evil all walls or objects 
calculated to confine or break sound should not be too 
far distant from the place of the speaker. 



ACOUSTICS. 19 . 

The form of the ancient theatres, the semicircular 
form, has been found altogether impractical for modern 
stage arrangements, and insuflScient for a large number 
of seats, the most important demand of the present 
day. The forms of the newer times which have been 
recommended and which have been executed are the 
following: 

1. An oblong, closing with a semicircle at the end. 

2. The semi-elHptical form. 

3. A part of a circle larger than one-half, or semi- 
circle. 

All these halls may have galleries, one above the 
other in similar outside lines, and should in all cases, 
except in very small buildings, descend towards the 
proscenium. In the old Academy of Music, the gal- 
leries descended 8 feet from the middle opposite the 
stage towards the proscenium. This mode of construc- 
tion allows better sight, and more seats are gained; 
another advantage is, the sound reaches directly to 
every spot without interruption, and it gives an in- 
creased perspective effect, which adds to the splendor 
of the building, and, in fact, transforms a theatre to a 
most cosy place. This arrangement should never be 
neglected, especially for opera houses, where most of 
the visitors desire to be seen in their costly attires, as 
well as to see. In planning the old Academy of Music 
I was forced to this arrangement, -viz. : the descent of 
the galleries, as the number of seats required was 
5,500, and without it many hundreds of seats would 



20 ACOUSTICS. 

have been useless. This immense descent of 8 feet, 
never knowa or executed in any other theatre before, 
was one of the main causes of the success of acoustics 
in that house ; the great number of seats in the gal- 
leries, seven and eight rows in depth on the side alone, 
demanded a great height of the building ; 78 feet was 
the height from the middle of parquet floor to the ceil- 
ing, and this space gave such a volume of condensed 
air that, without ventilation even, it would have secured 
at least for two hours' time a healthy and congenial air 
for sound ; but here I will add that all the walls, ceil- 
ings, gallery-breastworks, etc., throughout the house 
were covered with boards tongued and grooved so that 
every part formed a sound-board. The shape of the 
auditorium ceihng formed part of a circle, its centre 
point about 4 feet below the parquet floor ; this form 
is necessary to prevent the rays of sound from concen- 
trating more toward the middle of the building than 
toward the side walls. The outlines of the auditorium 
of the old Academy approached more the shape of a 
funnel with a semicircle at the end; the proportion of 
the auditorium was beyond any approach to known 
forms, the depth being about one-third more than the 
width ; a deep proscenium suggested itself to lessen 
the proportion, and this very depth of the proscenium 
proved most excellent for propelhng sound, as the air 
in the direct neighborhood of the originating point of 
sound became more dense, besides allowing a decora- 
tion so befitting for the frame which incased a living 
and most attractive picture. 



ACOUSTICS 21 

I win, howeyer, return again to the forms of theatres 
in use before mentioned. The oblong form, with a 
closing semicircle at the end, has many advantages ; 
it allows a plain construction and many seats, and in 
it the sound is clear from obstructions, and its action 
is clear and natural, but good sight could only be gain- 
ed by terracing the seats towards the proscenium, which 
would be unpractical for proper decoration, and would 
leave many seats near the proscenium useless. Three 
theatres only in Europe have come under my observa- 
tion ; one in France, one in London, and one at Mann- 
heim in Germany. To retain somewhat the advantages 
of the oblong form, the elliptical was substituted, with 
a partial success ; better seats near the proscenium 
were gained in comparison with the oblong. Dumont 
and Langhouse have written on this subject, and 
especially Mr. Langhouse, the architect of the Berlin 
Opera House, in his work considers the elliptical form 
as the best ; he sets forth many advantages : " He says 
there is no echo possible, and all the circular or rota- 
tory movements vanish." (Echoes are only dangerous 
in very large spaces ; but more on this subject here- 
after.) 

He states further : *' If the speaker places himself 
on one of the centre points, or nearly so, the rays of 
sound reflect only once, and unite in concentrating 
at the other centre points without causing any con- 
fusion." 

" Stiller," the great Prussian architect, sets forth hia 
objections to this form, and says : 



22 ACOUSTICS. 

1. " The distance of the hearers from the point of 
the speaker differs so much that an unequal arrival of 
the sound rays is the consequence." 

2. " The rays of sound will not be likely ever to be 
forwarded from one of the centres to concentrate and 
unite at the other centres all at the same time ; on the 
contrary, many concentrating intermixing rotary move- 
ments will be produced, and he points out, that, after 
all, the concentrating points for the rays are at the mid- 
dle, and adds, that in this very locality confusion takes 
place, or at least where the harmonious fulness of 
sound is lost, and gives as an example the Opera House 
in Berlin." 

To avoid all those difficulties, parts of the circular 
form were substituted till they reach the three-quarter 
circle. 

As I stated before, the semicircle, aside from the 
disadvantage of not allowing many seats, prevents a 
good connection with the proscenium. 

The circular or rotary movements, which take place 
in a full circle, are in a three-quarter chicle somewhat 
avoided, the proscenium placing a barrier in its way; 
and here it is to be added, that a large number of sound 
rays will extend to the stage and lose their strength by 
striking the flats which do not reflect, and no resound- 
ing or echo is possible; the partitions also in the gal- 
leries for the divisions of private boxes hinder the 
rotary movements. It is true there are even in the 
three-quarter circle rotatory movements, but they do 
not amount to any serious obstacle. The views of 



ACOUSTICS 23 

architects generally to remedy the evils of the before 
mentioned forms were manifold. I will here state a 
few more, merely for the sake of example and for the 
purpose of proving that after all these experiments, 
which were very good and laudable in themselves, the '» 
results were one-sided only. One of the many methods 
to assist sound was, to construct flues with openings, on 
the principal galleries opposite the stage, extending 
above the roofs like chimney flues to create a draft, 
but this proved a failure ; too much draft in those flues 
inconvenienced the hearers, and as the forward move- 
ment of sound is much swifter than the draft in the 
flues, the desired effect was lost. Another proposition 
was introduced to assist sound, and to prevent the 
rotary movement by constructing semicircular pro- 
jections like bay windows, in front of every private box, 
and this is reported to have done some good ; another 
proposed method is, to cover all the boxes with drapery, 
which deadens the sound completely 3^ an evil worse 
than the one to be superseded. A great evil caused 
by the construction of galleries, should be mentioned 
and noticed ; here, in soma American theatres, the gal- 
leries are very deep, in order to allow many rows of 
seats ; the projections of those galleries opposite the 
stage are often so large that they almost reach the 
middle of the auditorium, and the height from the floor 
to the lower front line of gallery breastwork or railing 
is seldom more than ten fee^t, with a ceiling un_dern,eath 
running parallel with the rows of seats somewhat shed- 
fashion; this construotioA nqt only preyents, the soun4 



24: Aoousrics. 

from entering direct, but gives tinder tlie galleries a 
most uncongenial place for sight and comfort. 

Perhaps a retrospective view of all the arrangements 
and evils connected with them, to gain intelligible 
sound, especially in theatres, here finds its proper 
place, and I will therefore proceed to explain why all 
of them have only partially succeeded. I say partially, 
because the results refer only to form, size, and ma- 
terials employed, although combined they were in- 
tended to promote good sound, and that failed. The 
experiments individualized the attributes of sound 
only, but the individuality of sound itseK, its living vi- 
tahty, its food, its digestive nature, was insultingly 
neglected, and its perplexing, stubborn, and resisting 
power was plainly visible, and so sound became a sub- 
ject looked upon as very fickle, unreliable, expensive, 
and even dangerous to be dealt with, and fell into ob- 
livion; but this status quo cannot last, this is sure ! so 
let us take it up again and try if we cannot push it 
forward, out of its stupor to its proper light, and instal 
it into that high sphere to which it belongs, and where 
it can shine as one of those millions of examples of 
God's wisdom in his beautiful and harmonious dictates 
of nature, which are all to our benefit and blessing. 

The human body, the lungs, etc., cannot exist with- 
out air, and so the voice, which originates from the 
body through air, which lives in air, operates in air and 
loses its vitality without it, should naturally lead us to 
the conclusion that sound can only be useful in a 
proper and healthy air, to such an extent as we require; 



ACOUSTICS 25 

and it appears that the same influences of impure air 
acting upon our feehng through our body are precisely 
the same influences which sound has to encounter. We 
often hear people say : I have made it a rule not to 
visit a business man on a rainy day on business 
of importance, as on such a day his mind is af- 
fected ; he has not the elasticity of mind to enter into 
a heavy business transaction ; and do you not find on 
a rainy day that the bells lose their distinpt sound, and 
even the rattling of carriages and carts passing in the 
streets is of less noise? don't you feel gloomy yourself 
on all such days, and restless ? do you not notice what 
a difference presents itself when you rise early in the 
morning and inhale a clear, fresh air, which gives you 
an elasticity mentally and physically? Ask the musician 
whether he does not notice a change in tone by such 
influences in the atmosphere ; ask men of science who 
make sound their special interest and digest over it, 
and examine its characteristics still more exhaustively, 
and you will come to the same theory which I have in- 
troduced, based upon my own past experience and as- 
sisted by inductive reasoning between known facts and 
phenomena and the laws or principles which govern 
them. 

The number of illustrations I introduced at the be- 
ginning showed the effects of the atmosphere upon 
sound, but keep in mind that the atmosphere which 
surrounds us in public buildings differs from the com- 
bined atmosphere of that grand space between heaven 
and earth ; this mistake has misled many architects in 



26 ACOUSTICS. 

their constructions, and to most ruinous results ; yes, 
I know of one large church, costing one million and 
a half dollars, which proved to be entirely unfit for 
use, and remains so up to this time. In this case the 
architect took it for granted that a cannon fired in a 
valley could not be heard on a high mountain, and 
vice versa, and he built a large cupola of great height, 
forming the main body of the church, supposing that 
the sound would not rise over 60 feet above the 
floor, a rule often introduced, but not applicable to the 
atmosphere contained inside of buildings, and there- 
fore took it for granted that the cupola above the 60 
feet could not be reached, and prevent the forward 
march of the sound ; but the very reverse result was 
noticed. With no ventilation to regulate the diflferent 
strata of air, the sound rushed up to the cupola in 
force, finding the lower strata of air heavy, causing 
a rotary circular movement of the rays, and, partially 
returning in a state of confusion, became wholly unin- 
telligible. 

The atmosphere in public buildings cannot be the 
same as the outer combined atmosphere. Why, the 
very fact that we are living in the lower strata of the 
atmosphere proves it, and hence it follows that we 
have in our buildings the lower strata of air in what- 
ever condition we find them, in their natural state, but 
condensed ; we often find them damp, heavy, cold, and, 
with too little ventilation, overheated. In public build- 
ings we have only one atmosphere to battle with, for 
our purpose a very lucky circumstance. Only imag- 



ACOUSTICS. 27 

inej if the inner atmospliere in a bnilding were exposed 
as mucli as the outer, the sound would be very often 
in the most intense state of excitement, and it would 
be impossible to arrive at means to prevent it. See how 
thoroughly that immense space between heaven and 
earth filled with air is ventilated ; to go into details 
and to understand them perfectly, would require the 
knowledge or theory of the wind, the evaporation pro- 
cess of the earth to produce clouds in order to replen- 
ish the earth for the loss sustained by the sun, etc. ; 
look at the daily changes of temperature, yes even 
hourly, the different seasons of the year, what does all 
this mean ? Why, ventilation, to give a healthy inhal- 
ing air to the living, and by the living I mean all ob- 
jects we see, that are full of life. 

Now let us see what we have done with this single 
stratum of air, a distinct atmosphere which is left for 
our buildings ; why, we have done almost nothing, we 
have not supplied it with sufficient fresh air, we have 
not regulated the different strata of air, we have not 
stopped the influence of the poison produced by the 
exhaled air, and left it often to the tender mercy of 
materials, which become dangerous by the neglect of 
this impure state, and these neglects have to be avoid- 
ed, or we can not succeed. Nature has helped us much, 
she has given us a condensed atmosphere entirely clear 
of outside influences, and this alone should be an in- 
ducement to relieve the evils mentioned, to prevent 
that cankerous odor of a stagnant atmosphere. Let us 
trace now how an impure air operates on the reflec- 



28 ACOUSTICS. 

tion of sound, and how all those movements so danger- 
ous to intelligible sound have been produced. 

In almost all cases in the present state of the at- 
mosphere in our public buildings without proper ven- 
tilation, the reflection of sound becomes confused by 
obstructions and angular forms in its march ; but the 
main cause of this annoying result originates more in 
the different strata of air, part of them being satura- 
ted with matter which is heterogene to the distribution 
of sound throughout, and which confines the sound to 
certain strata only ; and as the heterogene strata al- 
ways form their layers at the lower part of the atmos- 
phere, saturated by the exhaled air, and of a greater 
specific weight than the others, a distinct division of 
the upper from the lower is formed, and the upper, as 
likewise the lower strata become condensed. This con- 
densation in one sense should assist sound, and does 
so in all strata where the greatest purity of air exists, 
whereas in those strata saturated with impure air, the 
condensation actually stops the sound, and it becomes 
unintelligible to a certain degree, and in proportion to 
the volume of condensed impure air. This proves that 
the inner atmosphere of a public building under the 
influence of exhaled air, undergoes two processes of 
condensation, — the first one by the inclosure of the in- 
ner atmosphere cleared of the outer influences, and 
the second by the exhaled air of the human body, 
which becomes heavier, and through its weight the 
second process of condensing the inner air takes place, 
and this second process of condensation is the most 



ACOUSTICS. 29 

ruinous process to hinder distinct sound, especially in 
those places where the sound is most needed. The 
sound diiluses its rays immediately to all particles of 
the air, from its originating point of contact, provided 
the air is congenial ; but the moment the rays find ob- 
structions of a serious nature, they rise to other parts 
with more propelling power ; gliding over ^, even | of 
the volume of air contained in the building with con- 
tempt, and proceeding to the other part, they commence 
playful and vexatious tricks by rotary movements, by 
rotary concentrations, by resoundings, etc., and leave 
the audience in perplexity ; such phenomena you will 
find in very large buildings, where you would suppose 
that; the rays of sound, deprived of J and even of more 
of the volume of the inner atmosphere, find ample field 
for action. 

Echoes are never found in smaller rooms, but when 
a suflEicient interval exists between a direct and a re- 
flecting sound we hear the latter as an echo. " The 
reflected sound moves with the same velocity as the 
direct sound, so that in air of a freezing temperature 
the echo of a pistol shot from the face of a clift' 1,090 
feet distant is heard two seconds after the explosion." 

" In large furnished rooms, the reflection of sound 
' sometimes produces very curious effects. Standing, 
for example, in the gallery of the Bourse, at Paris, you 
hear the confused vociferation of the excited multitude 
below. You see all the motions of their lips, as well 
as of their hands and arms. Yon know they are speak- 
ing — often, indeed, with vehemence, but what they say 



30 ACOUSTICS. 

you know not. The voices mix with their echoes into 
a chaos of noise out of which no intelligible utterance 
can emerge. The echoes of a room are materially 
damped by its furniture." 

The presence of an audience may also render intel- 
ligible speech possible, where without an audience the 
definition of a direct voice is destroyed by its echoes. 

Sounds are also reflected by the clouds. 

" When the sky is clear, the report of a cannon on an 
open plain is short and sharp, while a cloud is suffi- 
cient to produce an echo like the rolling of distant 
thunder. A feeble echo also occurs when sound pass- 
es from one mass of air to another of different density. 
Thus by day the sound has to pass through an atmos- 
phere which frequently changes its density." Again 
I introduced a number of observations taken from 
English and German works, generally known, and find 
them corresponding in every respect. My intention is 
to introduce as many examples as possible, so that a 
more comprehensive view may be gained, especially by 
those who are less acquainted with this subject. The 
cause of echoes is here given, but it must be added 
that the sound will not reflect so intensely to repro- 
duce distinctness unless the form is of a pecuhar na- 
ture to assist ; this you will notice not alone in the 
outer atmosphere, but also in the inner, or in very 
large buildings, where the sound rays, owing to their 
direction of contact in sharp angles, reflect once or 
twice, causing a resonance, and returning in this con- 
dition to the ear. In a Merchants' Exchange, or in 



ACOUSTICS. 31 

any hall where hundreds of people are assembled, and 
where each desires his voice to be heard, confusion of 
sound naust take place, as the sound rays sent forward 
by each individual in different directions, fill the air 
with them, intermixed, and sometimes to such an ex- 
tent that it is impossible for a person to hear his own 
voice. One of these examples is found in the lower 
part of this city. In such cases it is difficult to reme- 
dy the evil altogether, because the atmosphere is over- 
taxed ; it takes the place of a servant who cannot serve 
two masters, and who recoils quickly at the imposition. 
But what can be done for a remedy ? First ventilate 
well, then cover the walls with drapery to deaden the 
sound, especially when the room is not in proper pro- 
portion to its height ; the third movement is to divide 
the ceiling by deep sunk panels ; if too late, divide the 
ceiling longitudinally and transversely by sheets of 
canvas not less than 3 feet in depth from the ceiling, 
which may be done with colored flags, forming some- 
what of a decoration. Ventilation will prevent the ac- 
cumulation of different masses of condensed air which 
in themselves would produce echoes, in many cases, 
the quantity of air not being sufficient for the number 
of people assembled. In smaller rooms like court- 
rooms, where only one voice is heard, a deep panelled 
ceiling would be injurious ; if you wish to convince 
yourself of this, visit the old court-rooms near the New 
Court House, in the lower part of this city. It was 
stated before that an audience may also render intel- 
ligible speech possible where, without an audience, the 



32 A€OUSTICS. 

definition of a direct voice is destroyed by its echoes. 
This is true, and may be accounted for by two distinct 
causes ; the first is, viz.: by the presence of an audi- 
ence the sound loses its aptitude to echoes, particular- 
ly if the audience is distributed over all parts of the 
house by galleries. The next cause is : the sound rays 
are intercepted in their forward movement, and vice 
versa in their return. In public buildings, or localities 
where the echoes are remarkably distinct, you may 
rely on it that the construction, the proportions, the 
form, and size is anything but suitable to the propaga- 
tion of good and intelligible soimd, and this proves the 
larger the area of an atmosphere the greater calcula- 
tion and knowledge of sound is required. 

It cannot be denied that the use of proper materials 
in the construction of public buildings forms an impor- 
tant attribute to the propagation of distinct sound, or 
at least to assist sound. If we examine musical in- 
struments, we find that wood forms the best material ; 
the thinner the sheets of wood used the more elasticity 
they gain, and the more susceptible they are to the 
rays of sound. The sound rays in their forward course 
through the air are assisted by its elasticity, and the 
moment they come in contact with the thin sheet of 
wooden wall they are restrained, but not suddenly or 
abruptly, as they find still an elasticity to work upon. 
The sound rays seem to be pleased with the natural, 
easy, and accommodating restriction; and especially in 
public buildings, theatres, etc., where the walls and 
ceilings are inclosed with boards, the sound seems 



ACOUSTICS. 33 

gratified to be restricted, conscious of its ability to go 
so far and no farther, to apply its force, and suddenly 
appear with a round, harmonious, clear and strong 
tone. But only then is it possible to produce this 
strength and clearness when there has been no ob- 
struction to the sound rays, and only through ventila- 
tion is it possible. 

In England several trials have been made with vari- 
ous materials ; for example, metal plates were put up 
to gain a sharp, penetrating tone, especially for speak- 
ing purposes, from the absence of elasticity being 
known ; but the result could not be expected to be 
favorable without the air being first cleared of all 
obstructions ; and even had the sound gained the 
sharp, penetrating tone, it certainly would not have 
been desirable any more than that emanating from an 
empty bowl or hollow pot. Notice the sharp, shrill 
tone of some of our clergymen in the pulpit, and 
actors on the stage, how disagreeable it appears, and 
with the addition of the sharp, trumpet-like tone of a 
metal plate would it not be shocking ? and I am bold 
to say, the sound rays would become a fearful chaos, 
and scare the audience to a quick exit. But wood we 
cannot always use for such a purpose, as the security 
of the building demands otherwise, and therefore 
hollow walls, either constructed of stud partitions 
plastered on both sides, or formed by furring strips on 
brick or stone walls, will somewhat assist; but it 
should never be forgotten that materials will only 
assist, not originate, the desired effect upon sound. 



34 ACOUSTICS. 

Many theories have been placed before the public ; 
twenty books on acoustics I had lying before me at 
the time I was on the point of building the Academy 
of Music. I felt that without some knowledge of 
sound I could not succeed ; and here was to be one of 
the largest theatres ever built ; a failure in acoustics 
was a failure in everything, so for eight days and nights 
I was engaged in studying those books, and after sift- 
ing them all I was placed in the most painful situation ; 
in fact, the nature of sound was a mystery to me for 
all practical purposes. In all those books there were 
not two authors who agreed; the very hobby-horse 
one rode, another tried to lame, or knocked under all 
four legs ; all the books proved a perfect mystery of 
scientific researches. Some of the authors went so far 
as to prove the rotation and reflection of sound by 
mathematical calculation, and illustrated them with 
thousands of lines, and with an infallibility perfectly 
perplexing; and others, again, had the audacity to con- 
tradict its truthfulnes, and still not one of those works 
had the merit of being generally admitted as correct. 

I was not aware that any more books could be found, 
so my last hope from that quarter vanished, and the 
only alternative was to fall back upon my own re- 
sources. I covered the whole interior auditorium with 
boards, hoping for success — and succeed I did ; but 
this success was not from the use of wood alone, it was 
from the immense inner atmosphere and other details 
which I stated before. Several city papers requested 
me, after the completion of the building, to publish 



ACOUSTICS. 35 

the secret of my success for the general good ; but 
how could I at that time, as I knew not how soon my 
hobby-horse would break down ? If my new theory 
proves correct — and I am convinced it will, although 
it may at first meet with some doubts — it will raise its 
head erect in the future when this particular branch 
of science, ventilation, shall reach its culminating point; 
then the atmosphere will be better understood, its im- 
purity, its outer influences, its quantity and quality ; 
then a new field will open itself, suggestions will spring 
into existence never thought of before, and those ob- 
jects that exist in air, that are influenced by it, and 
that cannot exist without it, will find their proper at- 
tention, but not before ! But there is no doubt it wil- 
be soon ; it is fortunate that ventilation must and will 
become a subject of great interest ; it has already be- 
come so ; it is necessary for health, the greatest bless- 
ing we can have. And why should not ventilation be 
introduced thoroughly in public buildings ? And who 
can doubt that these sound rays would find themselves 
at home; would they not playfully enter into every 
particle of air, and joyfully pay us with a salute of a 
round, clear, and strong tone, so pleasant to our ears ? 
I am glad to state that the principles of ventilation 
have taken hold in our country, perhaps generally 
more so than anywhere else. A new country like ours, 
with a population full of energy, and minds devoted to 
progress, cannot fail to take hold of rational ideas to 
further their interests. Ventilation would have been 
more extensively introduced, had it not been attempted 



36 ACOUSTICS. 

in many cases more as a means to make money than 
for any practical purpose, and it lias, in consequence, 
lost many warm friends, and has been actually an use- 
less expense to hundreds of citizens ; in many cases 
worse than an useless expense— more the means of de- 
priving them of healthy air than if it had been ignored 
altogether. This abuse, however, will rectify itself 
gradually. It is very difficult to introduce ventilation 
into most of our public buildings, especially theatres. 
I have had several cases where I used my best en- 
deavors to gain good ventilation ; in some cases thou- 
sands of dollars were expended for the purpose, and 
what did all my trouble amount to ? To nothing. 
Not an inquiry was made how the ventilation was to 
be applied. Lessees took charge of the building, 
ventilation became a laughing-stock to them; more- 
over, it would have required an intelligent person, 
with an expense of two or three dollars a night, to take 
charge and regulate it. But what can be expected 
from men who become lessees of a building for three 
or six months, with the determination, if possible, of 
placing two persons on one seat, without regard to 
danger of life, comfort, or health ? The condition of 
sound is never thought of — on the contrary, they are 
pleased for the same audience to re-appear to hear the 
other half of the sentence. Opposition is not expect- 
ed, as pretty nearly all theatres are alike, and con- 
ducted with similar management. I will not say all, 
but many of them. 



ACOUSTICS. 37 



CHUECHES, THEIR FORM, SIZE, MATERIALS, AND VENTI- 
LATION IN CONNECTION WITH ACOUSTICS. 

It is hardly necessary to point out the forms of 
smaller cliurches ; no matter what they are, they never 
affect the sound very materially, unless they become a 
hot-bed of bad air. The larger churches, which are 
now in demand, are the subject which I wish to intro- 
duce to the readers, a subject which must interest 
them, as all large churches in this country have proved 
failures in form and acoustics, to a most lamentable 
loss to their congregations, — one-half of the congrega- 
tion cannot hear, and in some cases the inner construc- 
tion is so arranged, as to lead a person to suppose, 
that the most necessary points, sight and good hear- 
ing, have been studiously avoided, in order to intro- 
duce impressions of strength, where actually a very 
small portion was needed, and this arrangement we may 
find in churches costing from 600,000 to 700,000 dol- 
lars . In one large church in this city where you can- 
not hear, the proportion or size would answer very 
well, but want of ventilation separates the aerial vol- 
ume into two distinct masses, the heavier part below, 
and the more flexible above; and, in consequence, the 
sound separates itself from the lower sphere, and rises 
to the higher, precisely where it is not wanted, and 
with a strength causing reflecting vibrations of a na- 
ture so monotonous as to create a sleepy sensation. 
There are two classes of large established churches, 



38 ACOUSTICS. 

namely, the Catholic and the Protestant, and each has 
its ritual, and has to be treated accordingly. 

At the present time the requirements of large 
churches are, that they be constructed with all possi- 
ble economy for good sight and hearing, and befitting 
the house of God, and that as many people as possible 
may be seated. How far these requirements have 
been complied with, the many examples rather of a 
caricature nature give a true synopsis of the actual 
state of religious feeHng of the present day. Every 
public building ought to be in reality the pulse of the 
inner life, and the house of God especially should not 
only be harmonious in its proportions, but of such 
construction as to stamp it with its true character so 
impressive to the mind of the beholder. 

Harmony, Science, and Art elevate us to a higher 
sphere of life, and should never be neglected in the 
house of God. 

" Many suppose that the Protestant churches are to 
be of an entirely different type to and in contrast with 
Catholic churches ; this is a great mistake ; the Refor- 
mation has not produced a new church — it has only 
assumed to have abohshed the errors and abuses of 
the Catholic church, and hence a new and specific 
Protestant style would be a foUy. In this field there 
could be no protest, only an acknowledgment and a 
necessity for reproduction ; and the best style will be 
the one which has the facility capable of entering into 
the smallest details of Christian and ecclesiastical 
spirit in the execution of the whole and in detail, with 



ACOUSTICS. 39 

a steadfast harmonious consequence, and calculated 
to represent a most intensive view." The Catholic 
church presents daily the holy rite of the Lord's Sup- 
per, and every person assembled on such occasions 
should have the privilege of seeing every ceremony in 
connection with it. The sermons which are preached 
are short, but from that very shortness they should be 
heard by every one, and well understood. It follows 
that a concentration of seats is necessary, with a direct 
sight of the altar ; this is the principal requirement, and 
how can it be done ? * The basilica is the oldest Chris- 
tian form of church, and will, if rightly understood, 
answer the purpose best. It is the most simple form, 
less costly in construction, highly favorable for decora- 
tion, and its perspective may even be extended to the 
effect of sublimity, and will admit of almost any style. 
It is true, galleries placed longitudinally in the 
basilica form will not be desirable, and they form in 
very large Catholic churches a serious obstacle for 
decoration. Now let us take a space of 65 feet in width 
and 250 feet in length including the chancel, with 
transepts forming a cross ; the number of seats may 
reach 2,800, each with a clear unobstructed view of the 
altar. The next demand is to supply a number of 
side altars, perfectly independent, with a separate pas- 
sage. This demand is met by placing the side altars 
on the longitudinal walls inclosing the side aisles, with 
10 feet for the altar, and a passage of 16 or 18 feet in 
width, say 28 feet in all will form two side aisles in 
connection with the nave ; and their isolation from the 



40 ACOUSTICJ. 

main body of the churcli will not only assist strength, 
but will allow a variety of form and of character most 
suitable to the church. The passage in front of the 
smallar altars will be a passage hkewise to the trans- 
verse seats of the main body of the church ; large open- 
ings communicating with the main body of the church 
are avoided, and the side walls of the nave are left un- 
disturbed for decoration, and facilitates the concentra- 
tion of sound. Ample light, also, is indisputably gain- 
ed by this arrangement. 

The front of such an inner arrangement will admit of 
two towers or one, and an exclusive field for the dis- 
play of the main front in its proper characteristic fea- 
ture noticed on all the basilica forms. 

Large door and window openings may find sufficient 
space, also, with an ample portico, etc.; a large church, 
built on this plan, will at once suggest how extensive 
a variety of form may be introduced ; it will admit even 
of six towers, with a cupola in the middle of the tran- 
sept, and an inner and outer decoration may be ar- 
rived at, worthy of the house of God. 

I will now proceed with the form, acoustics, and size, 
and prove that the basilica form, or oblong form, is 
much better calculated to assist sound than any other. 

A space 60 by 250, arched or covered with a hori- 
zontal ceiling, forms in itself a tube with a condensed 
volume of air, having the tendency to restrain the 
sound from spreading sideways, and to guide it in a 
forward direction similar to a pipe or tube, which we 
all know throws the sound to an almost incredible 



ACOUSTICS. 41 

distance. Notwithstanding this space is of large size, 
the influence, nevertheless, is the same. 

The fact is proved that the voice in large spaces 
may be heard 150 feet towards the front of the speak- 
er, 80 feet towards each side, and 60 feet to the rear ; 
this is, however, the extreme extent under very favor- 
able circumstances. This simple example shows how 
important form is in large churches to assist sound, 
and requires no further comment. 

Gothic arches have been considered an^ obstruction 
to sound, not only owing to their main elevating out- 
line, but more on account of their deeply recessed 
forms, which naturally create points for reflection in 
badly ventilated churches ; but large columns are the 
most objectionable parts of the church ; they not only 
obstruct sight, but give successive points for the re- 
flection of sound, and should be avoided in all cases. 

In the upper part of this city you will find a church 
in oblong form with a pointed roof, where you cannot 
hear ; this case seems to prove a contradiction, but by 
closer examination it is nothing but a natural conse- 
quence. The roof is put up in a very sharp degree, 
and rests on a wall not very high from the floor ; in 
fact this construction deprives the actual aerial space 
requisite for good hearing of about one-half of its vol- 
ume. As heat is introduced, the heated air rushes up 
to the highest point under the roof and there remains, 
and the sound, in consequence, operates in this very 
spot so congenial to its nature, and, reflecting from 
one side of the roof to the other, bses its effect entirely 



42 ACOUSTICS. 

on the assembled multitude. A sound-board has been 
introduced, but cannot be of any favorable result. In 
the beginning I referred to art being necessary to con- 
struct buildings for public purposes, and equally so for 
large aerial spaces. Art teaches us to create proper 
proportions, and this very aesthetical feeling requisite 
to do so, should at once put a stop to those low pro- 
portioned ceilings which always form an eyesore to the 
cultivated mind, and especially in a church ; good pro- 
portioned halls will always prove to be correct and in 
harmony with the aerial space necessary for good ven- 
tilation and hearing ; it is strange, but nevertheless 
true, that nature and science go hand in hand, and to 
succeed it is absolutely necessary to be perfectly at 
home with the study of the different branches of sci* 
ence and art. 

Church architecture of the middle ages proves the 
spirit of that age; religious feeling was at its highest 
point, and was sure to produce the most subUme 
effects human nature possessed, but nevertheless it 
has proved to be one-sided, after all ; it carried the 
human souls too far above the sphere of our worldly 
life, and could not exist for any length of time. We see 
what art was capable of performing, stimulated by 
religious feelings ; but that time has passed away, and 
we are now in a sphere of worldly materialism. The 
present churches prove it ; a change is desirable, and 
would it not be best, at least, to profit by the golden 
grains left to us, and add practical alterations for good 
sight and hearing in our future construction of churches 



ACOUSTICS, 43 

and other buildings, so that the house of worship, as 
well as the lecture-room, will become more attractive, 
and assist the advance of human progress ? Let us do 
away with heavy stone columns, introduce iron col- 
umns as sight requires the change, and confine our- 
selves to those forms best adapted to the purpose, and 
churches and other buildings will present an attraction 
of a powerful nature to lead the aspiring individual 
and penitent sinner to his home. Very large supports 
or columns in our churches only obstruct the sight 
and sound, in fact, they are merely introduced for an 
imposing effect, nothing else, as the ceilings of almost 
all our churches are constructed of wood and plas- 
tered. Iron columns will answer the same purpose as 
to strength, and are more in keeping with the con- 
struction. In some churches in this city where stone 
piers are introduced, the amount of their cost would 
have actually been sufficient to construct the entire 
building fire-proof, with iron and bricks, and the 
building would have exhibited a greater aerial space 
and a clearer sight in the interior. Iron construction 
will eventually step in; although many will protest 
against it, it is the only construction for our present 
wants, especially where galleries to any extent are 
required. 

Iron construction in the interior of churches and 
public buildings is not new ; in secular buildings we use 
it daily, but in the interior the iron constructions are 
very seldom modelled to answer a constructive part of 
decoration, in which there is a large field for improve- 



M ACOUSTICS. 

ment. In Prussia iron construction is already intro" 
duced in clinrclies and other buildings with artistic 
skill ; and it certainly should not be neglected in this 
country. 

Now we will examine the wants of Protestant 
churches of smaller and larger size. It will not be 
without interest to add a few remarks relative to the 
progress of Protestant churches up to the present 
time, to prove how large a field there is still open for 
the future in this particular branch. 

" In Prussia and in England this interesting subject 
has had its due weight, and progress has been made to 
a certain extent. In Europe, for the past 2| centuries, 
the Protestants have been content to use the Catholic 
churches that fell to their inheritance, and in the erec- 
tion of new churches they have followed the plan of the 
Catholic churches, with the introduction of plain galle- 
ries, and without any metaphorical decorations." 
" In England, in Protestant churches, in their inner 
arrangement, the vigorous zeal to conform to the pres- 
ent demands was first visible." " In Germany (Prus- 
sia) " Schinkel," the great architect, was the first who 
appeared as a reformer in this direction, and a num- 
ber of his plans show a distinct separation from the 
main body of the church and tiie chancel, inclosing the 
altar service and a distinct Baptistery. Somewhat la- 
ter this direction was followed up, and two scholars of 
*^ Schinkel," two very eminent architects in the Prus- 
sian service, were ordered to visit England and other 
countries, to inform themselves of every new arrange- 



ACOUSTICS. 45 

ment that might have been made, and after their re- 
turn they exhibited to the Prussian Government a 
number of plans of churches for villages and for cities 
of smaller dimensions ; these plans were all adopted by 
the Prussian Government, and ordered to be published 
as a standard to be followed in all new constructions 
of similar demands. The plans of the smallest 
churches published, in almost all cases represent the 
oblong form ; the body of the church is undivided, gal- 
leries are mostly left out, the ceihng always construct- 
ed in wood, and the construction itself in every plan is 
taken up as a motive for decoration and inner life." 
"The chancel inclosing the altar service, is mostly 
closed in an apsis form, very seldom in a straight line ; 
the pulpit is placed sideways before the altar, where 
the chancel comes in contact with the body of the 
church, and on the side of the altar generally termed 
by Catholics the evangelical side. The font is placed 
in the longitudinal axis of the building, below the lev- 
el of the steps leiading to the altar. The exterior is 
very plain; burnt brick is the prominent material. 
To harmonize with the material, and to give life and 
character, the principal forms of the middle ages are 
predominant ; a more picturesque than severe style of 
characteristic, however, is introduced." This very 
picturesque stamp would be very desirable for our vil- 
lage churches, and for smaller cities, where the monot- 
ony of frame buildings is too frequently visible. It is 
true, the English in their churches have often made 
the attempt to create picturesque forms, but each na- 
tion seems to have its own peculiar taste* 



4:6 ACOUSTICS. 

" That the small Protestant churches in their whole 
form cannot deviate from the Catholic church or 
chapel is a natural consequence ; only larger dimen- 
sions will cause the historical forms of the CathoKc 
church building to come in conflict with the material, 
and partly, in a certain sense, with the ideal demands 
of the Protestant churches, and consequently in laiger 
Protestant churches a peculiar varying formation be- 
comes a necessity, and a discriminating character is 
only then possible, and so the characteristic of large 
size churches will depend on the form, the manner, 
and the place allotted to the pulpit and font, and in the 
arrangement of galleries ; besides those positive 
changes, there are some more negative variations of 
rather smaller interest." 

" The plans published by the Prussian Government 
for churches of middle size are of the oblong basilica 
and central square polygon form, somewhat like the 
Grecian cross. Churches of those named forms are 
best calculated for Protestant churches ; the voice of 
the clergyman is better heard in them ; they admit of 
deeper galleries, and seat more people." 

" The Catholics, however, at this newer time often 
introduce galleries, and nobody can deny that they are 
very useful ; the opinion of the past eighteen centuries, 
that churches shall not be constructed for profitable 
theories, is laid aside and somewhat antiquated. Very 
large Protestant churches will have to fall back upon 
the plan of the oblong form with galleries, with a 
similar arrangement first described for Catholic 



ACOUSTICS. 47 

chtirches." The extent of hearing has its limit, and if 
we require churches of immense capacity we have to 
fall back on forms which are calculated to assist sound, 
with good ventilation. The basilica form may be 
extended to 300 feet in length; but concentrated forms, -- 
such as the square, will never answer the purpose for 
good hearing. A very striking example is one of the 
churces in the upper part of this city, not very large, 
but nearly square ; the sight is good, but the sound 
quite unintelligible in many parts of the building. It 
is not alone that the inside proves how little the form 
was understood, but more striking by the outside. 
The form of the church represents a barn with an im- 
mense roof. The two towers in front are a mixture of 
Gothic and Romanesque, the Gothic elevated spirit 
predominating strongly in contrast with the body of tho 
church, rarely to be seen. In this church we find two 
elements ; the one has special claim to materialism, 
and the other to an aspiring sphere, a most inhar- 
monious whole, and unfortunately the aspiring spirit is 
on the outside. 

To characterize the interior of the church in front 
was an impossibility ; if it had been insisted on, the 
bam form would have been still more strikilig, and 
therefore the architect felt himself bound to place two 
elevating towers in front to hide the mistake, and es- 
pecially in such a prominent situation. True harmony 
can only be produced, if the inner life is strictly follow- 
ed in the outer forms ; in this case the galleries are 
secondary, and form no principal divisions in the inte- 



48 ac6UkST1cs. 

rior, consequently the towers are inorganically con- 
nected with the body of the church. Square forms of 
large size, or those nearly square, require an entirely 
different arrangement, and should never be used for 
very large churches ; aside from acoustics, larger sizes 
of timbers are necessary, and the decoration has to 
be rather pretentious, or the building will look empty, 
and will more or less leave an impression of monotony. 
" In very large Protestant churches, where galleries 
Lave to be introduced, and on a large scale, the oblong 
form, with nave and two side aisles, becomes a neces- 
sity ; in such cases it is desirable to add a transept of 
sufficient projection to allow more concentration. With 
entrances or outlets on each side, with enclosed pas- 
sages and stairs leading to galleries extending the main 
body of the church from front to rear beyond the 
transept, with one division beyond the transept ad- 
joining the chancel, and allowing the centre division of 
the transept to be double in size in comparison with 
the other divisions, and three of the smaller divisions 
for the body of the church in front, a concentration is 
gained with two side aisles and nave which wUl give a 
grand aerial space, and admit of a large number of 
seats around the pulpit. The pulpit may be placed on 
the side of the column at the intersection of the nave 
and transepts, and a richly decorated chancel ; the 
whole will produce an opulent and rather an unusual 
arrangement, only noticed in large cathedrals. This 
will be the form for large Protestant churches, and no 
other ; but we must not forget that there is a certain 



ACOUSTICS. 49 

extent in size which we cannot overstep." Churches 
with transepts in connection with side aisles, even 
with two or more aisles ; polygons, no matter of 
what form of plan, will eventually assist much in the 
formation of public monuments to comply with all our 
wants ; and the Catholics will, if they do not insist 
upon retaining large surfaces of walls for other pur- 
poses, use similar forms, as they have done already in 
some cases, and fall back upon the original form of the 
divided oblong. 

" It cannot be doubted that a centralization of form 
appears to have advantages ; but, after all, it will not 
compare with the oblong form, which concentrates the 
view to one spot only, viz. : the altar, the most promi- 
nent point ; and it suggests itself that central forms for 
churches have not been based upon the requirements 
of the liturgy ; altogether, to produce a majestic and 
imposing effect, which conforms to the early Christian 
works of this class, it is not to be wondered that the 
noble construction of a cupola, in its inner and outer 
grandeur, and with the charming effect of the upper 
light in contrast with the more plain form of the basil- 
ica, should have been favored. The obloDg form, 
with only one division, will centralize to a greater 
extent than more ; but the construction of monumen- 
tal buildings in this form becomes expensive owing to 
its great height in proper proportion, whereas in divi- 
ding the width of the building into nave and two side 
aisles, the height is much diminished in proportion to 
its width. The idea of building churches and even 



50 ACOUSTICS. 

theatres to contain from four to five thousand seats with 
a clear sight and with perfect acoustics, is a mistake, 
and can only be entertained by architects who are 
strangers to science. Three thousand five hundred 
seats placed in one space, with comfort, forms the 
culminating point of hearing, and any attempt to 
extend the number of seats further rests on an assump- 
tion of knowledge which does not exist. All the reports 
spread abroad that there are churches and theatres 
containing five thousand seats, is an error; and if there 
should be a building of such a class, you may be sure 
that you cannot hear in all parts of it. Now I will 
present the reader with facts relating to the minimum 
extent of aerial cubic feet requisite for good hear- 
ing, facts which I gained by many years observations 
in examining buildings where the acoustics are con- 
sidered good, and public buildings, theatres, and 
churches of the largest size which came under my 
direct care. Churches, halls, lecture-rooms, etc., con- 
taining not more than one thousand seats, should not 
have less than 150 cubic feet aerial measure for each 
person. 

Churches containing 2,000 persons, not less than 
from 250 to 300 cubic feet aerial for each person, and 
an increase to from 300 to 500 in proportion to the 
number of persons ; 500 cubic feet aerial will answer for 
3,500 persons, even 550 cubic feet aerial will not be 
out of proportion with a calculation of about 6 square 
feet to one seat; if more, the aerial space will consume 
too much sound and will lose its force. Five hundred 



/ACOUSTICS. 51 

cubic feet aerial space will keep an audience pretty 
comfortable for an hour, as to breathing; but never- 
theless, the sound begins to rise after this space of 
time, and appears distinct for a short period only, 
emanating from the pulpit about 10 feet above the 
floor, but loses its strength gradually, and then the 
lower strata of air become specifically heavier and 
the sound less audible, and persons occupying tho 
principal seats in the nave naturally suffer the most. 
A thorough ventilation with proper form to assist 
sound, wilU be absolutely necessary to remedy tho 
difficulty. All the above aerial proportions will, if 
properly applied, form another link of the consistency 
of nature, which never deceives. 

It may be readily seen that a proper ventilation, 
consisting of a proportionate supply of fresh air, and a 
proportionate outlet of bad air, is as necessary as the 
sound itself, for sound, to be distinctly heard ; and 
hence it follows that churches and theatres with abun- 
dance of aerial measure, are often better adapted for 
hearing than buildings of a smaller size, where the air 
is impure and has less opportunity to diffuse itself, and 
the necessity of ventilating smaller public buildings is 
in one sense of more importance than in larger build- 
ings ; this depends, however, solely upon the time of 
actual use. A church, or a theatre, or a lecture-room 
occupied for one hour's time, will prove better for hear- 
ing than for two hours, and so on ; and halls occupied 
the whole day, like the Senate Chamber and Hall of 
Representatives in the Capitol at Washington, without 



62 ACOUSTICS, 

the proper aerial measurement and with insufficient 
ventilation, prove failures. 

In all cases where a public hall is occupied for half 
a day or more, an increase of aerial measure for each 
person should be adopted, as the present mode of 
ventilation cannot be relied on. 

The form of our churches which we see daily in this 
city and in the country, with immense roofs resting on 
stone walls only 10 feet high, and sometimes divided 
in the interior into nave and side aisles, with a 
high tower on one of the corners, is an attempt to ele- 
vate the building to a characteristic which it does not 
deserve, and may be termed an excessive economical 
measure, regardless of the inner life, placing the eleva- 
ting spuit on the outside only. And the church com- 
mittee who protests against such unnatural forms 
should receive thanks for unerring zeal, if only rest- 
ing on an intuitive feeling of propriety. 

Wooden ceilings and open roofs are often very desi- 
rable and have many advantages, but they should 
never be used except for smaller churches ; they will, 
if properly arranged, allow a very desirable decoration 
for the interior. The open roof allows more height 
for the interior of a church, and may be placed on 
^ much lighter walls, by which expense is saved ; but 
in many cases the roof forms the most prominent part 
of the church, and such extremes lead to caricatures 
of a most striking nature. 

There is no cause for fear that the open timber roof 
diminishes the church -like appearance of the interior, 



ACOUSTICS. 53 

if the constructive timbers are only properly arranged, 
and treated with a fine sesthetical feeling, with suitable 
mouldings, etc., and harmonizing colors, a most beau- 
' tiful and impressive effect is gained ; but in large 
monumental works the arch has and always will be 
the most effective form for an impressive and elevating 
characteristic. 

Hitherto it has always been noticed that the ceilings 
of churches and of other public building have had an 
important influence upon acoustics ; and wooden ceil- 
ings and groined arches have proved to be better 
suited than the semicircular arches, etc.; this is very 
true, and could not have been otherwise ; but groined 
arches, and even wooden ceilings, as we often see 
them, have in many cases created bad effects. In one 
church in Fort Wayne, State of Indiana, constructed 
with a wooden ceiling, it was impossible to hear, and 
the confused echoes were actually sent forth from this 
wooden ceiling. I could mention many examples of 
the same effect, and why ? From the want of ventila- 
tion, the force of the sound was concentrated to the 
ceiling alone, and through its force those very phe- 
nomena were visible ; and so it will be with any arch, 
and especially with a cupola, that rises above the level 
of the church ceiling. The heat will rise to those 
parts and invite the sound to follow, and it does follow 
with force, and its general diffusion throughout the 
church is lost. Now, is it not easy to comprehend 
that if the air in a church or any other public build- 
ing is heated equally, and the ventilation good, the 



54 ACOUSTICS, 

diffusion of sound will be more equal throughout every 
part, and that the reflection of sound, caused by pro- 
jections and recesses will be less, especially when the 
points of contact are at a considerable distance ? At 
this very moment I have received from Berlin an 
architectural work in which Dr. Dove, a Professor of 
Science in BerUn, and a very eminent man, gives his 
views relative to the rules of acoustics, to be observed 
in the erection of a new dome or cupola in the city of 
Berlin. His treatise is interesting, and I think a 
translation into the English language will not be out 
of place, as I intended to proceed with the same iden- 
tical subject. 

" The problem which has been stipulated upon 
practical acoustics can be named as the very reverse 
to that which optics have to solve. All the rays 
which emanate from an illuminated body shall be con- 
centrated into a point to reproduce the same picture, 
which on that account could only be discernible at a 
certain point, whereas the sound rays shall be equally 
distributed, so that no one individual, placed at a cer- 
tain point, shall alone hear the orator, but large num- 
bers placed at different points shall hear him equally 
distinctly. The ages of antiquity have done nothing 
to assist practical optics, notwithstanding they have 
done more in single cases than the present age for 
practical acoustics. The point of view which has 
guided the architects of the past ages in their con- 
struction of temples and theatres appears to be 
entirely of an empiric nature, and in fact a greater 



ACOUSTICS. 55 

experience was at their disposal as long as comnrani- 
cation was predominating, based upon the living word 
in its place ; writing was very little known, and print 
altogether unknown. Besides, the recitative may 
often have been substituted in the place of the com- 
mon speech, for report says that an orator of the olden 
time required a musician of the flute to direct the 
tone of his speech. It may be taken for granted that 
a thorough theory relating to the propagation of 
sound rays was entirely out of the question, and 
particularly at a time when experiments were un- 
known. It is only in this century that the laws in 
which sound in its commotion and in its propaga- 
ting oscillatory motions have been settled, and hence 
science is too young to fill the chasm left by Antiquity 
with precise theoretical observations. Tones called 
forth, directly perceptible at a certain point, can be- 
come indistinct when the sound waves, emanating 
directly from the sounding body agitated at other 
points, come in contact with each other, or by their 
self-created reflections from various objects. The 
surrounding stillness requisite to distinct hearing will 
obviate the first difficulty ; in the second case, which 
demands here especial attention, there are several 
species to be discriminated. Since the propagating 
sound waves are actually produced by their succes- 
sively following condensations and attenuations in 
equal distances, and by the intersection of the sound 
rays at certain points when their paths, crossing in 
different lengths, happen to meet with the condensa- 



66 ACOUSTICS. 

tion produced in one case, and with the attenuation in 
the other. In this case the air will not be condensed 
or dilated ; stillness is produced by the converging 
sounds of the same height, however oscillatory the 
motion may be, which increase or decrease the force 
of the tones, if the respective contrast of the conden- 
sation diflers in each case whenever the rays cross 
each other. 

We will designate this problem with the name inter- 
ference. But the deeper the tone the greater the differ- 
ence between the condensation and attenuation ; for 
instance, by the deepest sound of our organs 16 feet, 
and by the highest sound of the human voice | inch, 
and in consequence some sounds at a certain height 
may be destroyed and others become perfectly clear. 

The enclosure of great spaces for acoustic purposes, 
rendered necessary by our climate, naturally increases 
the stipulated reflections in a manner unknown in the 
ancient theatres. 

By the medium temperature of Berlin (7° R) sound 
passes through a distance of 1,050 Paris feet in a 
second, at the freezing point 333 metres. If a reflect- 
ing wall is at a distance of 525 feet from the point 
where the sound emanates, and it strikes directly 
upon the surface, it will return in a second to the 
point of emanation. The nearer the wall the quicker 
the reflection follows the sound, as it is impossible 
to distinguish more than ten tones in a second if the 
distance is about 53 feet. The smoother the reflect- 
ing surface, the more the reflecting sound increases to 



ACOUSTICS. 57 • 

a certain extent. But for the long sound waves the 
surface which is considered coarse for light is already 
to be viewed mirrorJike. To diminish and control 
the condition and effect of the reflecting sound rays 
can be correspondingly acted upon in two ways ; first, 
by changing the surface of the reflecting walls, and 
secondly, through the form applied to them. 

The result in lessening the reflection will be that 
the irritated tones will operate the same as those pro.- 
duced in an enclosed space. It is evident that the 
effect in an enclosed space which produces tones 
depends much upon the points where they are pro- 
duced or created. In a circular building there are 
naturally many points which in relation to the reflec- 
tion of sound compare equally, as all points corre- 
sponding to the circumference of a concentric circle 
comply with this condition. In the centre the echo is 
stronger because the reflecting rays all of one distance 
must accumulate in their effect. A most astounding 
example is the arch of the cupola of the old Museum 
of Berlin. And likewise is the centre the point from 
which the words of the speaker are most homogene- 
ously heard if the seats of the audience are arranged 
concentric, similar to those in an amphitheatre. The 
theatre in the villa of Hadrian at Tivoli, the circus of 
Murviodore, the amphitheatre at Nismes, prove this, 
as all the words uttered in the arena are distinctly 
heard at all points. The voices of singers, however, 
become entirely inverse if seated on concentrated 
seats ; the voice unites harmoniously in all parts. For 



58 ACOUSTICS. 

cliurcli music, however there is very seldom such an 
arrangement. An astounding effect I had an oppor- 
tunity of noticing in St. Paul's Cathedral in London. 
Amphitheatre-like seats were erected for three thou- 
sand orphans, directly under the dome, and when 
the sioging commenced the effect was sublime. 
The more remote we are from the centre point 
the less will be the equal perceptibility on all points 
of the circle ; for, if the sound rays are noticed 
which spread perpendicularly on the radius of the 
curve, it is plain to see from a simple plan that on 
certain points many reflecting rays cross each other, 
and in other places only a small number, and it follows 
directly that the perceptibility on various points must 
be very different. This conforms also to the hori- 
zontal section (a well-known example of which is the 
whispering gallery in St. Paul's Cathedral, London), 
as well as to the perpendicular section of cupola 
arches. It is the case here, as in the Palace chapel in 
Berlin ; by placing singers on a continued gallery 
under the cupola-arched ceiling to perform church 
music, the music is distinctly heard by every one, 
whereas the voice of a clergyman placed in a position 
not high above the altar will produce reflection of 
sound unintelligible at many points. 

The difficulty of the problem to erect churches 
with good acoustic qualities depends in general on 
very different conditions, to comply with all of which 
simultaneously would be impossible. 

The spoken words do not require an identical con- 



ACOUSTICS. 59: 

stniciion of the interior for good hearing with that 
requisite for a musical piece, if they were even ema- 
nating from one point; and this fact prevents con- 
versational pieces being carried out in opera-houses 
with any success ; and from this very cause it is im- 
possible for the voice of a clergyman to fill the space 
of a dome, originally intended for the execution of 
grand musical compositions to accompany the mass. 
In public speaking the strength of sound is much im- 
paired by the walls producing reflections, and hence 
less distinctness; whereas the walls of the concert-room 
are often lined with wood, to give a higher and more 
marked tone. And from this very cause, too, pianos 
which are for sale are placed on elevated reverbera- 
ting platforms or floors, as curtains, tapestry, carpets, 
richly cushioned chairs, will materially weaken the re- 
sonance. In St. Paul's Church, in Boston, it is said 
that the clergyman is only beard at Christmas time, 
the church being then decorated with drapery. Can- 
on Mills proved perfect in regard to acoustics for the 
service of the meeting of the Free Church in Scotland, 
as long as the walls were left unfinished, whereas oth- 
er buildings with finished walls showed most impor- 
tant acoustic defects. The cause of these difterent ef- 
fects of the walls on speech and sound is this, they add 
force to countless consonants, and a noise is produced 
which does not appear when clear tones are constant- 
ly repeated. A covered space in form of a prolonged 
square or oblong, has proved to be best for acoustic 
purposes, provided the tones originate on one of the 



60 ACOUSTICS. 

smaller sides, and that the place of the originating 
tones be higher than the space filled with hearers, so 
that those seated in front may not intercept the tones 
from those seated behind. In this case the forward 
moving sound rays are especially directed to the space 
occupied by the audience. The Berlin Singing Acade- 
my proves itself in this respect perfect. Should it be 
desired to give more distinctness to the words, a half 
cylinder might be added to the extended square, and 
with such a curve that the reflecting sound rays from 
its own walls follow parallel with the more extended 
sides of the square. With a parabolic curve, the speak- 
er should be situated at the focus of the parabolic 
transverse section ; with a spherical, his standpoint 
should be at the distance of ^ of the radius from the 
middle of the surrounding walls. Should the building 
be arranged for both hearing a speech and a musi- 
cal piece, a diflferent point would have to be selected 
for each ; for the orator, the end of the building, with 
the cylindrical curve, and for music (organ and church 
music) the shorter and straight side of the extended 
square. These main conditions have been generally 
introduced into Christian churches, and the basilica of 
the ancients has been their model. 

The main ground form of the basilica forensis was 
an oblong or extended square, with a semicircular 
apsis, and an elevated tribune adjoining for counsel- 
lors, with a small vestibule enclosing the whole. width 
of the building on the opposite side of the niche. 
The semicircular extension is about one-half of the 



ACOUSTICS. 61 

middle part of the whole building, which proved good, 
practically, and authenticated, by the speaking-tube, 
that the voice of the speaker is much strengthened, 
when, from his stand-point, the sound rays are more 
restrained from spreading sideways. The proportion 
of the transverse section of the semicircular apsis to 
the width of the building had the tendency, in the 
construction of churches, to cause the division of the 
space by columns, into a nave, with two side aisles. 
At the place of the Chancellor's seat, in the Basilica 
Dominica, the Bishop's cathedra, semicircular with 
his Presbytery, was substituted. But in front of the 
nave and side aisles a transverse space of larger width 
was introduced, and, later, the transept, which estab« 
lished the cross form of churches, with the altar in the 
middle. Then, the Bishop's chair was removed farther 
to the rear, with an enclosure to confine the lower grade 
of divines, whereas the nave and side aisles were al- 
lotted to the people. On the side of the three main 
divisions, the altar-house, characteristically marked by 
the direct adjoining quadratic space, and the transept, 
with a triple width of the chancel, and the main body 
of the house, with the nave ; the first two were higher 
than the third. Below them, often a " Krypta " was 
found, and sometimes, a passing street. The eleva- 
tion of the chancel is one of the most important ar- 
rangements for acoustics, and this arrangement has 
been essentially retained also in Gothic buildings, only 
differing in the continued curve being changed to the 
polygonal. If the transept is further removed from 



62 ACOUSTICS. 

the chancel, then the ground form changes to that of a 
perfect cross. By adding to the cylindrical extension 
the whole diagonal section of all the divisions of the 
church, then the acoustic requirements are partially 
assisted ; then, also, a passage round the chancel may 
be arranged so that the chancel may retain its smaller 
proportions. The grand effect of church music in 
large spaces is, undoubtedly, enhanced by the right 
angle form ; the broken lines of the arches, the large 
openings left on the upper parts in the side walls of 
the nave, and sound openings in the ceiling, are of the 
greatest importance, especially in very large churches, 
where a possibly created echo may be removed by be- 
ing intercepted. On the whole, in reference to sym- 
metrical arrangement upon the longitudinal axis, no 
intimatioa is in existence of a demand in such a 
building to gain a third point acoustically, ia compari- 
son with the end point of the longitudinal axis. 
"Where, ii]a.en, shall the pulpit be, as the sermon forms 
the centre of gravity of the Protestant worship ? It is 
architecturally so disturbing to the eye, that, in the 
Basilica in Munich, when not in use, it is always 
moved aside. 

Here are then only two ways open, either not to use 
it or to preach the sermon from the altar. In a Gothic 
building of large dimensions the voice will be more 
distinct if the pulpit is placed in a position where the 
hearers may have a chance to gather in a large open 
space. 

Without the detailed plans of the new Dome 



ACOUSTICS. 63 

building about to be erected, I consider it impossible 
to decide on the most proper place for the pulpit, and 
especially, as undecided problems cannot admit of 
solubility; the more so, indeed, if from the beginning 
no satisfactory solution has been admitted. In general 
it appears to me, if the original type of our churches 
is retained, the corner pier will be the best, where the 
transept connects with the body of the church. The 
voice enters then into the crossing divisions diagon- 
ally, and at this stand-point, moreover, is the freest 
space. Still more difficult does the problem become if 
the galleries with a terrace-like arrangement are intro- 
duced — for economical purposes. Walls forming 
divisions must then be avoided. 

According to my view, it would be proper to make 
on .the plans certain points at which to place the 
pulpit without infringing too much upon the architec- 
tural effect, and after the building has been sufficiently 
advanced, to examine the acoustic effect of each, and 
then to select the best place." 

This last named article, written by Dr. Dove, is a 
very able and distinct synopsis of the past and present 
state of the known theories, confining the sound rays 
of speech and musical tones to their limits and effects, 
up to the present day. All the details given are, no 
doubt, very precise, and, as generally established, 
based upon science. Now, my readers, I have intro- 
duced this article not alone owing to its great interest 
and value, but at the same time to form a solid basis 
to rest upon, and to prove how little reliance can be 



64 ACOUSTICS. 

placed on a theory of supposed causes and effects 
which do not actually exist. We all know that 
there is no certainty of constructing public buildings 
thus far perfect and distinct for good hearing ; and 
yet clear and distinct speech in a public building is 
most important. Now, as I stated before, a mere 
accident led me on to the astounding result, that a 
clear and healthy air is necessary to restore distinct 
sound in a public building where not more than twenty 
minutes previous the air was found in a chaos of 
mixed impurities. 

Dr. Dove bases his experiments upon a medium 
temperature of 7° K. in Berlin, and gives his results 
as to the strength and effect of sound rays. This 
may be all very correct, but has absolutely nothing to 
do with the effect of sound in public buildings. The 
Doctor's experiments refer to the actual state of the 
outer temperature alone, which does not exist in the 
inside of a building. The inner atmosphere, and the 
temperature in an occupied and inclosed space, with- 
out proper ventilation changes every minute, and the 
sound rays become irritated to a degree fatal to dis- 
tinctness. Enough has been said referring to the spe- 
cific gravity of the different strata of air, to prove how 
the exhaled air affects the aerial space ; and the diflS- 
culty is that the sound rays always following the most 
flexible air, become isolated or distinct in their field 
of operation, and hence, in this more confined portion 
of the aerial space, must naturally increase in force, 
and create resounding effects, and become mixed and 



ACOUSTICS. 65 

unintelligible. It is perfectly clear that a certain force 
concentrated in one spot, must have results which will 
materially differ when the force is distributed ; does 
not daily life prove this assertion ? 

If the sound rays are spread throughout an aerial 
space, say in an occupied church, will they act with the 
same force on the curved ceilings, or even on the larg- 
er pillars ? Why, the strength of the musical tone is a 
proof of itself. There is no difficulty for musical tones 
to be heard more distinctly in any aerial space, owing 
to their greater force ; the force is strong enough to 
penetrate into all strata of air more or less ; but still, 
even with this propelling force, the tones are often di- 
rected to separate parts of tha building, influenced in 
the same manner by the variations of the temperature, 
and condition of the various strata of air. The exam- 
ple and effects of the variations of speech, and the ef- 
fect of musical tones, directly under the dome of St. 
Paul's Cathedral, in London, is introduced by Dr. Dove 
as a most unmistakable phenomenon ; but it must be 
added, that in this case the difficulty for speech is 
more than in any other locality, as the dome itself is a 
condensed tube with an upward direction, carrying 
the voice with it ; and it follows that domes and 
certain parts of ceilings carried above the general lev- 
els, will always have a restraining influence in propa- 
gating sound. The effect of the speaker's voice, plac- 
ed only a few feet above the level of the floor, is lost 
upon the gathered multitude, and why? First, hu- 
man bodies deaden the sound, and the heavy strata of 



66 ACOUSTICS. 

air whicli always commence to accumulate at the floor, 
are equally obstructive, and it follows that the floor 
seats in a theatre or in a church, are the very seats 
where you hear least distinctly, but the moment the 
speaker takes a higher situation, say 15 feet or even 10 
feet above the level of the floor (this means the level 
of his head above the floor), the voice becomes more 
distinct. An arrangement to be recommended in all 
churches and pubHc buildings. 

Now let us take a general view o^ all the difficulties 
we have to contend with in our aerial spaces to pro- 
duce clear sound. In fact, the difficulties are great, 
and it is only in this century we begin to comprehend 
how the sound rays move, and on a retrospective view 
of centuries we cannot be right in confining ourselves 
to the attributes of sound only, such as size, form, 
and material, and by substituting external aerial effects 
for those which exist in the interior of a public build- 
ing crowded with people, never ! "We must ignore all 
those difficulties first, and examine the condition of t^e 
inner atmosphere of a crowded house, and then we 
shall find ourselves in a new field of operation. Who 
can say that a condensed air mass of all kinds of 
impurities will not affect the sound rays more or less 
in its force to penetrate ? Let us hold on to all the 
forms, size, and materials which have the tendency to 
assist sound in its progress and effects, and furnish a 
pure air through ventilation ; then sound will be in its 
natural element, and perform its duty. The perfect 
chaos of theories introduced to assist sound have so 



ACOUSTICS, 67 

far in one sense actually been detrimental to any 
advance in this branch of science ; a perfectly repel- 
ling influence has been the consequence; and how 
could it be otherwise, with so many theories presented ? 

Now, the next question will be, how can we procure 
a pure and healthy air in our public buildings ? In an 
auditorium occupied with people, say two hundred 
persons, allow four cubic feet of fresh air per minute 
for each individual, also the total amount per second 
2^^ = 13 1- cubic feet. It must not be neglected that 
the capacity of the flues for escape of impure air 
should be at least one-fourth larger than the supply- 
ing flues. 

In concluding this subject, I will here add, that this 
new discovery to gain intelligible sound through ven- 
tilation, settles this fact, that sound depends princi- 
pally upon a clear and pure air for intelligible hear- 
ing, and is not dependent on the attributes of form 
and materials altogether. But the moment we im- 
prison or inclose the sound, the sound becomes imme- 
diately restrained by form and materials in its natural 
action, and proper form and materials become a ne- 
cessity to guide the sound rays to their proper chan- 
nel and extent, with proper clearness. And as this 
application has not been sufficiently attended to, fail- 
ure has been the result. 



68 HEATING AND VENTILATION. 



GENERAL VIEWS OF HEATING AND VENTILATION. 

Ventilation has not yet arrived at perfection to a 
point of matlieinatical precision ; but this, although 
desu-able, is not absolutely necessary. Heating and 
ventilation are branches of science which have re- 
ceived thus far, a general acknowledgment, embodying 
principles of the greatest importance; but the applica- 
tion of those principles for practical purposes has 
proved insufficient. How pressing this deficiency has 
been felt, is proved by the various experiments intro- 
duced, even on the largest scale ; thousands of dollars 
have been expended to gain the point of a healthy cir- 
culation of air, in some cases with more, in others 
with less success. 

Now, let us trace, from those many experiments, 
and their failures, the truth of the above assertions. 
All the appliances, either natural or artificial, to gain 
a healthy circulation of air have proved insufficient, 
and this fact leads to another important one, that the 
atmosphere with direct and indirect influences has not 
been properly understood, or else the appKances 
would have been difterent. 

What fault can we find with the present systems of 
ventilation and heating? Why, the fault is this: 
Public buildings have been only partially ventilated 
and heated, and the air contained in them revolu- 
tionized more or less, without regard to the natural 
consequences arising from such arrangements. What 



HEATING AND VENTILATION. 69 

constitutes a perfect ventilation ? Nothing more than 
a moderate and equal temperature throughout every 
part of the building, consisting of a fresh and healthy- 
air in a continued flow of supply and proportionate 
escape without any perceivable motion. The air con- 
tained in a building, especially when filled with people, 
is in a continued state of chemical mixture ; yes, the 
materials of the surrounding walls, ceilings, etc., have 
their influences likewise, and this chaos of influen- 
cing matter is to be removed, or the air cannot be 
healthy, and those same influences lead sound to its 
natural grave. 

I will here introduce an example given by " Dr. J. 
Berger," to prove how variously the temperature of air 
confined in a room heated by a stove is affected, and 
at the same time give a clear view of the present sys- 
tem of modern heating. 

"In a room 20 feet long, 10 feet in width, and 11 
feet high is placed a cast iron stove, near one of the 
corners, immediately opposite a window on the longi- 
tudinal side of the room. 

" By an outer temperature of 2° E., a thermometer 
protected against the morning rays of the stove showed 
the following result : 

At the floor. At the ceiling. Loss 

1' distance from window 10°5 ...... 19° 8°5 

At the middle of the room 11° 20°5 9°5 

1' distance from the stove 12° 23° 11° 

" This proves that the air of the lower part of the 



70 HEATING AND VENTILATION. 

room towards the floor has about half as many de- 
grees E., as the air at the higher parts. You will read- 
ily notice the immense loss of actual warm and service- 
able air to the inmates. The healthy remedy general- 
ly acknowledged to keep the head cold and the feet 
warm, could not be applied with such a conflicting 
temperature. On the contrary, the head in its natu- 
ral position would be warm and the feet cold. This 
process of heating by the stove, applies more or less to 
all heating methods now in use, as every one of them 
leads the warmer air to the ceiling of any room or hall 
etc., allowing the heat in the downward march to be 
absorbed by the windows, w^alls, etc., and scarcely 
warming the lower cold strata of air where most need- 
ed ; and in this lower strata is the resting place of the 
organic impurities caused by the exhaled air, evapora- 
tions, etc., producing the actual poison which the lungs 
detest, and sound abhors. No mode is hitherto known 
of measuring those mixed quantities of impurities 
in the air with precision. To come to any near ap- 
proximation, we must first calculate the amount of car- 
bonic acid contained in the air, and allow that the 
quantum of the organic impurities are proportional to 
it. The next point will be to confine the carbonic acid 
as represented by the most able searchers into the va- 
rious methods, and with the general result, to prove 
that the substance and quantity of the carbonic acid 
is to be found in the upper parts of an inhabited room 
to a much greater degree than in the lower. The 
cause is as plain as important. The lower part of the 



HEATING AND VENTILATION. 71 

air becomes warmed througli the bodies, and rises 
with the mixture of impurities, and at a higher point 
follows the draft to colder parts of the room, and sinks 
mixed with fresh air, penetrating through the pores 
and smaller crevices somewhat diluted, to unite again' 
with the organism. If it were possible to stop this 
downward movement, and carry off this impure air af- 
ter rising, out of the room, then the carbonic acid 
substance would never be noticed, no matter how 
large the assembly of people, or how strong the gas- 
light might be ; but as the impure air will ever repeat 
its downward movement, so it will repeatedly enter the 
lungs and affect the system most dangerously." Here 
is the boundary where words must become deeds ; this 
sickening air must be driven away without mercy, and 
then we shall have arrived at a point to benefit the hu- 
man race ; health and acoustics will shake hands, and 
public buildings will become a focus of pleasure and 
attraction ; many valuable lives that adorn the pulpit 
will be saved from their early graves. How many 
children who are now prisoners in the unhealthy strata 
of school air, for a number of years, and return to 
the new paths of life diseased, will, when all the evils 
have vanished, return in a healthy and vigorous state 
to practical life. 

Now, we should suppose a speedy remedy could be 
found to overcome the above-mentioned evils, but let 
us not be too sanguine ; it will not be found for some 
time to come — not until every person, or at least, a 
large number of an intelligent class shall become fa- 



72 HEATING AND VJENTILATION. 

miliar with this branch of science ; then architects and 
doctors will be forced to fall into line like the soldier 
into the line of battle, not to destroy, but to rescue 
valuable life. So it is with art ; is it ever acknowl- 
edged, without a general knowledge and appreciation? 
Let us hope that the time will soon come when science 
will assist and guide us to our duties. It was not my 
plan at first to enter into the details of ventilation. 
My intention was, to give a general view only of the 
present mode of heating and ventilation, and to draw 
attention to the want of its proper application, so far 
as in my power, but a few days ago I received a new 
work on heating and on ventilation, by Dr. J. Berger, 
written in the German language, which gives many il- 
lustrations and suggestions, and with such clearness and 
adaptation to the purpose, that I thought it best to in- 
troduce some of them, with the hope that they may in- 
terest the public upon that important branch of sci- 
ence : 

" As soon as a stove, placed in a room, begins to 
throw out heat, so soon the former perfectly calm air 
will be drawn into a most lively and disturbed move- 
ment, and this movement you may readily notice by 
placing yourself before a window ; a sensible cold air 
draft will meet you, no matter how perfectly the windows 
are closed ; this cold air draft commences whenever the 
heating begins, and it cannot be denied that it has 
originated from the interior of the room. Now", to il- 
lustrate more clearly this singular movement, let us 
t^ke the most simple method of tracing it with a small 



HEATING AND VENTILATION. 73 

piece of burning tinder. Hold this burning tinder 
near the stove, and the smoke will rise on the sides 
and on the edge of the projecting top cover, but in the 
middle of the cover it becomes restrained, and, unad- 
justed, is driven back to the edge of the cover, and 
from thence it rises again. If you hold the tinder 
somewhat higher above the top of the cover, then the 
smoke will partially rise and fall towards the middle. 
" These simple experiments give us an insight to the 
previous examples. It is evident that the air is drawn 
from around the stove to the stove itself, then becomes 
heated, and rises upwards in a lively upward current 
on all sides ; but it is equally evident that the heated air 
above the cover will be dislodged and replaced by the 
hither flowing cold air. But the colder air can only 
flow from the direct neighborhood of the stove, and 
naturally must intercept the flow of air which has been 
rising on the sides of the walls at different places, often 
changed and precipitated upon the middle of the cov- 
er ; it then becomes heated and rises, and, pressed on 
the upward flowing air, is immediately carried with it 
in close proximity to the edges of the cover. Further 
above the cover, where the colder air ceases to sup- 
ply, only an upper current of air takes place, and the 
smoke of the tinder above the cover is carried upwards, 
and its course can be traced to the ceiling of the room. 
This will occur in a similar manner with larger heat- 
ed surfaces. If we notice the course of the ascending 
air, and observe the direction in which the smoke of 
the burning tinder, placed at various parts of the room 



74 HEATING AND VENTILATION. 

is forced, it is easily perceived that from the upper 
parts of the stove the main flow is toward the win- 
dows and the colder walls of the room, and from 
.thence in a sinking condition again retraces its steps 
[towards the low^er parts of air surrounding the stove. 
By lifting the burning tinder in one part of the room 
gradually higher, you will notice how the smoke is 
stronger below ; but the higher above, the weaker it 
is driven towards the stove, till the smoke at last rises 
perpendicularly ; however, it soon changes its course 
in the reverse direction. On the walls near the stove, 
where they are somewhat heated, the air does not de- 
scend, but rises naturally upwards. This illustrated 
rotary movement bases itself upon the very plainest of 
fundamental laws. This law is the following : The 
heavier liquid always falls to the lowest spot. The 
air cooled by the windows and walls contracts by this 
influence, and, with an addition to its specific weight, 
sinks to the floor and presses the warmer air upward, 
and in such. a manner that the higher it is placed, the 
higher the temperature is marked in the thermometer. 
• ^' Near the stove the air receives its progressive move- 
ment to the highest temperature. As soon as the air 
becomes warm, that moment it is pressed by the ad- 
joining cooler air, upwards, and then flows to the more 
distant parts ; and in one place the cooled and specifi- 
cally heavier air is continually pressed downwards, and 
at another place, the warmer and lighter air is contin- 
ually carried upwards, and so the rotary movement 
takes place consistently with the law of nature. But it 



HEATING AND VENTILATION. 75 

is not to be understood by this that the heated air 
possesses an inward natural tendency to rise, and that 
this tendency is really the originating power to cause 
the movement. This very mistaken idea seems to 
have been the cause of many errors of the past, and 
has led to many costly experiments. The greater the dif- 
ference of temperature between the several air masses, 
the more energetical, and the more quickly successive 
the rotary movement wUl be. It is known that the air 
in a gassy condition dissolved contains more moisture 
the higher the temperature, and that the heated air 
withdraws the moisture from the walls. After the air 
has been in a considerable degree cooled down, then 
it is forced to submit to the laws of its moisture, as the 
cooling process deprives it of the dissolving quality, 
and so the windows become covered with it. In a 
room where the moisture is increased by cooking, 
washing, and by exhaled air, etc., the moisture settles 
on the cooler parts of the walls, particularly behind 
beds, wardrobes, etc., and, as the moisture possesses 
mixtures of other substances, the more it is to be com- 
prehended that, in this condition, ample cause is given 
for a mouldy and putrefying process. It is an error to 
open occasionally the door of an adjoining cold bed- 
room, rarely ever aired ; there the moisture begins 
to form its malignant effect on health. In such rooms 
fungi are formed, and a whole family, who occupied 
one of those rooms at night, during a whole winter, 
were reduced to a most lamentable state of health. 
The people cannot be warned enough against such 



76 HEATING AND VENTILATION. 

mistakes, particularly from the evil effects not showing 
themselves directly ; they are, on this very account, 
more dangerous." 



MODERN VENTILATION. 

All the phenomena referring to this subject may be 
traced more or less to the movements of water on the 
principle of communicating pipes. For instance, if 
two perpendicular pipes are connected by another in a 
cross direction, and filled with fluid, for example, 
water, then the water will rise in both of them to an 
equal height. If different fluids are poured in, then 
the height of the fluids will be inversed according to 
their specific weight. If the liquids are quicksilver 
and water, the quicksilver in one of the pipes will, for 
example, be one foot, and the water in the other will 
stand 14 feet high ; and it is of no consequence 
whether the two upright pipes are equal in size or 
different. If we take it for granted that one pipe is 
only one foot, but the other 15 feet long, if the latter 
pipe is continually filled, the water in the short pipe 
would break forth to the corresponding level of 15 feet, 
and it certainly would gain this height if its flexibility 
did not produce a considerable diminution. There 
are two causes which take the advantage of the flexi- 
bility. The one is the weight. This weight draws the 
rising water parts, the higher they are the most en- 
ergetically backwards, consequently the upper parts 
will always rise more slowly, and prevent the lower 



HEATING AND VENTILATION. 77 

from a quick upward movement, and with a pressure 
causing the parts to shift to a sideward direction. So 
the water jet spreads out upwards in a conical form, 
and loses in height whatever it gains in the transverse 
section. The second cause, the resistance of the air, 
operates similarly, and this force parts the rays pos- 
sessed with the natural tendency to the formation of 
drops, and assists them in innumerable parts to a re- 
peated downward fall. The lighter the rising fluid the 
less the influence of weight; the influence of resistance 
however is greater, to which we must bestow our most 
particular arttention. If we place a pipe one foot in 
length in a high wash-bowl, and fill it with spirits of 
wine, which is lighter than water, but heavier than air, 
and let the water rise through the spirits, the resist- 
ance would be still greater. We should notice the 
rising stream easily, and should be able to discern it 
more distinctly by its coloring the water, and then we 
should notice that the jet of water upwardly would 
spread quickly, and by no means rise as high as for- 
merly in the air. If we allow the jet of water to play 
some time, then the spirits of wine becomes more 
watery, heavier, the jet wider and lower, till at last, 
dissolved on the bottom, it becomes immovable. The 
' more compact the middle in proportion to the liquid, 
which moves in an ascending stream within, the more 
it spreads, and the nearer to the bottom. All the facts 
alluded to above will assist and enable us now to a 
clear conception of the former remarks in our system 
of ventilation. A very effective and plain ventilation 



78 HEATING AND VENTILATION. 

may be gained at a trifling expense in rooms where no 
calculation for ventilation has been made. At any 
point in a room wherever a good connection with the 
outer atmosphere can be made, place a pipe of tin or 
of any other material, several feet long, perpendic- 
ularly, and inserted in the floor, with elbow at the 
lower end to connect with the outer air, the pipe or 
pipes to have both ends open ; let their diameter be 
two or three inches, somewhat in proportion to the 
room ; in a small room only one inch diameter. As 
soon as the room is heated, no matter in what manner, 
the outer air enters the pipe, but does not sink into 
the lower strata of air contained in the room, but rises 
with increased rapidity in proportion to the increase 
of heat. If you enter in very cold weather into such 
a heated room, you will notice a powerful air draft, 
even at a considerable distance in height, and by 
placing the hand on the inner opening of the pipe it 
is pressed upwardly with great force. If we place 
a short pipe in the ceiling of the room, and con- 
nect it with the outer air, the eff'ect will not be 
changed; we shall find precisely the same result as 
with the other arrangements. In place of the water 
we have the cold air ; in place of the spirits of wine 
we have the warmer and lighter air of the room or 
saloon, in which the cold air penetrates through the 
short pipe. If the room should be empty of air, then 
the air-jet would spring to the ceiling. The greater 
the difference of the outer and inner temperature, the 
nearer we approach this case, and the lesser the resist- 



HEATING AND VENTILATION. 79 

ance, the higher in proportion rise the rays over the 
heads of the inmates. A water-jet always returns to 
the earth, but it is different with the rising air-jet. 
The more it comes in contact with the dissolving 
warmer air, the more quickly it receives the warmer 
temperature, and the more quickly also vanishes the 
tendency to descend. The entering fresh air steps into 
the circular sphere of the existing impure atmosphere; 
one part of the mixed air escapes through an opening at 
the ceiling. It is noticed that the greater the difference 
of temperature between the inner and outer air, the less 
the inmates gain by the entering fresh air, notwithstand- 
ing the greater influence of the cooling process. The 
higher the saloon is, the farther in height reaches the 
difference of temperature between the inner and outer 
air ; the higher also you calculate the outer pipe to be, 
the higher will ascend the rays of fresh air. 

From the preceding, it follows, what opinion we may 
form of another application that has often been made. 
Basing upon experience, that the air in the upper parts 
of a heated room is warmer than in the lower, open- 
ings have been inserted in the walls close to the floor, 
to allow the impure air to escape with as little loss of 
heat as possible. That the lower air of a room is cool- 
er than the upper is certain, but it is equally certain 
that the outer atmosphere is still more so, and natu- 
rally the one enters through the flues inwardly, while 
the other passes outwardly. This and similar arrange- 
ments lead to that great fundamental error. The heat 
is furnished to the upper parts, whereas the intention 



80 HEATING AND VENTILATION. 

and desire is to use it at the lower. All tlie impuri- 
ties of the air wander inseparably wdth the heat ; to 
restrain and let them escape from the higher strata of 
the room, has been unsuccessfully attempted. To at- 
tain the first point actually, the second is gained, and 
to attain the latter you infringe on the other. The 
Doctor says, in a large saloon in Frankfort, a large flue 
was constructed, with an opening of 6 or 6 feet from 
the ceiling. Through this flue it was intended the 
warm and impure air should escape to the outer at- 
mosphere ; but the very reverse movement took place, 
and the cold air rushed into the saloon with such ve- 
hemence that the dra^ft had to be stopped immediate- 
ly. In the Hospital La Riboisiere at Paris, the cold 
air, with the same arrangements, poured into one of 
the wards, notwithstanding the fresh air was, in great 
quantity, forced in by a machine. Now let us be clear 
on these proceedings. If we fill a glass with water, 
and fill a small pipe with quicksilver, and expect that 
the water will raise the quicksilver, and then the quick- 
silver rise of itself, everybody would at once wonder at 
such a demand ; in one case the quicksilver and in the 
other the heavy air descends towards the bottom, and 
the water pressed upwards will overflow in the same 
manner as the lighter air is carried higher in the sa- 
loon. Should it be desired, however, to let the air es- 
cape through the flue under the ceiling, then it would 
be necessary to heat this flue still higher than the 
temperature of the hall. But what would be the re- 
sult if a flae was to be extended inside the wall to the 



HEATING AND VENTILATION. 81 

floor and heated as it is often done ? It is evident 
that the air rising from the stove, and with it its im- 
purities, descends again and repeatedly, to reach the 
opening of the flue, and the impurities, or at least a part 
of them, will again enter through the lungs. There ap- 
pears now, from the former mentioned case in which 
the cold air descends to the bottom, and from the one 
preceding, in which, under similar circumstances, the 
flow or current is upwards, to be a contradiction in itself. 
This, however, is only apparently so. If the flue with 
an outlet 5 or 6 feet below the ceiling of the saloon 
had been extended to the floor, then the air, by suffi- 
cient difference of temperature, would have been equally 
vehement in rising, but would not descend. In the 
first case, the descending air follows the law of weight, 
the same as dropping water ; liquid bodies spread all 
over the bottom and press the extended aerial masses 
higher. In the second case the air follows likewise 
the law of weight ; it cannot spread apart at the bot- 
tom of the flue ; it must, by the assistance of the pres- 
sure of its additional weight, force the lighter columns 
of air higher. But this is not the warmer air of the 
saloon, it is the former descending cold air ; it is, how- 
ever, now concentrated from the former field of action, 
and the whole pressure acts upon the transverse sec- 
tion of the ascending flues. If the cold air had, for 
example, covered the whole extent of the saloon 
floor, 1,000 square feet, one foot high, the adjoining 
warm air would have been forced up one foot higher 
also ; and if the height of the saloon had not exceeded 



82 HEATING AND VENTILATION. 

ten feet, 10,000 cubic feet of air would have been 
forced upward one foot. And notwithstanding the 
transverse section of the perpendicular ascending flue 
should contain only one square foot, 10,000 cubic feet 
of air would have been raised one foot in the same 
time. The laws of nature are infallible ; if parts 
of a mass can move without obstruction, they certainly 
will regulate themselves according to their weight; the 
heaviest will seek the lowest, and the lighter by 
degrees higher positions. Resting upon this law, we 
are accustomed to see the ascending air from the 
stove. This is really the case, provided this law has 
its fair field to operate upon ; if not it will fail. The 
Doctor gives here an example of a Foundling Asylum. 
The building is two stories in height, and to supply 
fresh air in the second story wards a hexagon tower 
was constructed over the roof, from which four hori- 
zontal air channels or flues were placed in connection 
with the tower, and extended under the roof, with an 
outlet very ingeniously arranged to receive the outer 
atmosphere. With those flues large canals were 
connected with the basement, and from them branch 
canals led the air to the first and second stories to 
supply circular cast-iron stoves surrounded with 
chambers to receive the cold air for heating purposes, 
similar to our furnace arrangements. The most 
particular examination has given the following 
results : Nearly one-half of the movements proved 
unfavorable; one-sixth part entirely contrary to 
that required. The difficulty, it is stated, gener- 



HEATING AND VENTILATION. 83 

ally took place at night, v/henever a brisk wind 
arose from any direction. The very reverse move- 
ment to that required was so strong, that the 
wards often became very cold, and in the flues the 
temperature of 30*^ was noticed. Now let us place 
this arrangement before us on a smaller scale, which 
may easily be done. Two perpendicular upright stove 
pipes communicate and connect at the lower ends by a 
short horizontal pipe. In this last named pipe hot 
coals are placed, so that the nearest adjoining upright 
pipe is heated; and let us call the heated pipe the hot, 
and the other the cold. A lively cold air stream will en- 
ter the latter, and an equally lively warm one will escape 
from the first. By blowing inwardly into the hot pipe 
the flow will be reversed in the one inwardly, and out- 
wardly from the other. If the blowing is stopped, a 
moment's pause will take place, and then the flow will 
return to its original course. By making the cold air 
pipe smaller than the hot, then the reverse movement 
is less likely to take place ; the greater the difference 
of the longitudinal section, even should the cold air 
pipe be extended to twice or three times the length of 
the hot, if you blow into the latter a reversed move- 
ment will quickly follow, the more so the longer the 
cold air pipe is; the moment we stop blowing, this 
flow will with less facility return, and will with more 
energy persist the longer in it the longer the pipe is. 
Should we make the cold pipe shorter than the hot, or 
insert an opening at the bottom of it, the return of the 
proper movement would take place. It is also easily 



84 HEATING AND VENTILATION. 

comprehended that the return may be gained by 
blowing into the cold pipe, and it is also easy to give 
an account of the proceeding. The air expands with 
each degree of heat 0.00366 of its volume. If heated 
to 100"^, then its volume will increase about one-third 
more than in its former state. If the two pipes con- 
tained an equal volume of air, then they must have an 
equal height; and if the one is heated to 100^, then the ' 
one-third of its air is naturally warmer than the whole 
volume of the other; consequently the latter is pressed 
out, the colder air enters the hot air pipe, becomes 
equally warm, and meets with the same fate as the for- 
mer air that was pressed out. If we blow into the hot 
air pipe, then the heat is carried from that pipe to the 
horizontal piece, and to the cold air pipe, and as a mix- 
ture takes place, it is plain that in the cold pipe the 
heat cannot be as great as in the hot, notwithstanding 
the flow of hot air ; the return is easily possible, par- 
ticularly if the cold pipe is smaller. Should the latter 
be double the length, then it will contain two volumes 
of air with a heat of 100^ with | loss, and the loss of 
heat in the short piece proves itself iosignificant. It 
follows, now, that the upper volume of air in the short 
heated pipe will use its pressure, the outer the same 
as the inner ; consequently two volumes press against 
1| volume. A voluntary turning is not possible to take 
place. If we open the cold air pipe near the bottom, 
or shorten it, then the cold air will flow in, the warm 
air column will be less, and an inversion will take 
place. The more easily the pipes can be heated, the 



HEATING AND VENTILATION. 85 

better conductors of air they will be, and the more dis- 
criminating will easily connect the phenomena with 
the observation. The shorter piece may play a very 
important part. The longer it is, the more difficult 
will be the return. There is not only a restraint by 
the admissibility of heat, but also by the friction 
affecting the inner passing flow of air. By canals or 
sewers below the streets in which the draft of air is 
under the same influence of the laws demonstrated, 
this vertical pipe is to be compared with the sewer 
itself ; if very long or extensive, this influence is great. 
It is not necessary to mention again the case referred 
to, that of supplying the stoves in the Hospital wards 
with cold air. What we gain by blowing inwardly can 
in the other case be effected in various ways, some- 
times under favorable circumstances by closing a door. 
Whenever a strong wind blew into the tower, and 
consequently into the wards, a reverse shock towards 
the tower had to follow, similar to the effect of a 
strong wind upon an inward folding window partly 
open. With a great heat in the stoves, the return 
movement naturally took place, and it would have 
occurred much oftener had the tower been more ele- 
vated above the level of the stoves, or the warm air 
columns supposed to be extended to the ceiling of the 
saloon. This example proves that the ventilation in 
the wards of the first story was worse than in the 
second. The flues or canals referred to in the Hospital, 
which connected with the two stories and communi- 
cated together, would naturally have caused an over- 



86 HEATING AND VENTILATION 

flow of bad air from one story to the other. The 
flues from the basement to the ceiling of the second 
story were larger than those to the first ; it follows, 
therefore, that the flow of air from the first to the 
second story was more easy than to a reverse move- 
ment. The latter movement could only be produced 
by the heat in the first story being strong, and in the 
second much milder. It is equally as easy to demon- 
strate that the northern half of the building is more 
calculated to assist the functionary movement than 
the exposure of the southern half a whole day to the 
sun, as that the whole arrangement proved less satis- 
factory in the hottest part of the day. We see, there- 
fore, from the aforesaid, that the whole error of the 
arrangement consists in this, that the cold air has been 
conducted from the highest point with much cost, 
whereas it should have been drawn from a deep place, 
and with less cost. The mistake could have been 
remedied in a simple way, viz., by shutting up the 
upper arrangement, and by constructing a cold air flue 
from the basement descending towards the garden, 
where the flow would have been inwardly at all times, 
and the warm air would never have suffered any loss. 
The idea to lead the fresh air upwards from a hot 
stove, as was the case in the Hospital, appears on first 
sight impractical, but with a closer inspection it is 
found otherwise. By the former example before men- 
tioned it is explained how the cold air is driven up- 
wards in the warm saloon, and it follows hence that 
we should take notice practically of the ascending 



HEATING AND VENTILATION. 87 

rays. The heated air masses near the stove are the 
hottest in the whole saloon, and even without the outer 
pressure the upward flow, on account of its higher 
temperature, will rise to the highest points of the 
saloon. But the greater the difference of tempera- 
ture between the inner and outer air, the more ener- 
getical will be the ascending movement. If there is a 
number of openings, as there should be, placed at the 
highest points for escape, then it is clear that the 
newly entered good air escapes without any benefit 
to the inmates whatsoever. The impurities exhaled by 
human bodies with less temperature will rise more 
slowly and less high, and only part of them will be 
forcibly carried away with the ascending draft. What 
can be expected to be retained in the saloon? A pro- 
portionate small part only of the direct supply of 
good, and a very large part of impure air. The cal- 
culated mixture and amalgamation will be only in a 
small degree. This evil, nevertheless, will remain the 
same, no matter whether the openings for escape are 
there or not. The healthy air will in this case escape 
through occasional accidental openings, particularly in 
the higher strata. 

It is hardly necessary to state that the air ventila- 
tion finds here its proper place also, and that it is 
impossible for screens, no matter how they are made, 
to prevent the evil, and we may base on this so evil a 
circumstance, the cause that the ventilation through 
warmth has furnished such bad results, while through 
a mechanical action of force a greater agitation, and 
consequently a general mixture, takes place. 



88 HEATING AND VENTILATION. 

" But it is likewise true that the difficulties of the one 
and the other method are attached to each, though in a 
different degree. In all arrangements in which the 
hot air is introduced immediately under the ceiling, 
and the impure colder air, as mentioned before, escapes 
through heated channels or flues with considerable 
expense, the great difficulties are then partially over- 
come, but others before explained remain. I will here 
mention another characteristic error, which is seldom 
noticed. It will perhaps set aside any doubts that may 
still exist. A large escape-flue is constructed above 
the ceiling, to allow of an escape of impure air. A 
strong heat is introduced in the upper part of the flue, 
for the purpose of gaining a strong draft. Now let us 
return to the plain pipe, and place hot coals, not on 
its bottom, but on a wire-net arranged so that it may 
be raised and lowered in the hot air pipe, and then 
hold a slip of paper over the cold ; you will per- 
ceive that the flow of air becomes weaker the higher 
the wire net is raised, and on the contrary that the 
deeper it is placed, the quicker will be the flow ; a 
result which is easily explained. If the wire net or 
the warming spring is placed in the middle of the hot 
pipe, the air volume below the middle part of the hot 
pipe will be of the same temperature as that below the 
middle of the other hot pipe. Hence it follows that 
the two air volumes will hold their balance, and the 
difference in their weight above the middle, would be 
equally as great as if the connecting pipe were placed 
at the same place. The higher the warming spring is 



HEATING AND VENTILATION. 89 

placed, the shorter the communicating pipes are, the 
less will be the difference in weight, and the less the 
draft, but larger the expense of the fire material. The 
aforesaid facts prove how easy it is to penetrate any 
system of ventilation, if we only fall back upon one or 
the other simple experiment, by placing stove pipes 
together in form of communicating pipes. It cannot 
therefore be difficult to follow every new case that may 
arise." 



HEATING AND VENTILATION OF THE ANCIENTS. 

" Many will hesitate to admit that the ancients were 
ever acquainted with the principles of economical and 
rational process of heating, and to do justice to the 
necessity of an effectual ventilation. This assumption 
will not alone be justified by their knowledge, of 
science, but also owing to their mild climate ; lUrge 
meeting-houses, or public halls, to accommodate 
thousands of people closely huddled together, were 
less in demand than at the present time by our social 
dispositions and climatical demands. Dr. Berger, 
however, in his work, states that it is very interest- 
ing to prove that the ancients in their simple and 
serene sense of nature actually did heat and ventilate 
better than we do at the present day, and adds, that 
it will be absolutely necessary, if we intend to arrive 
at some perfection in this particular, to fall back on 
the principles by them introduced. If we intend to 
make ourselves better acquainted with their arrange- 



90 HEATING AND VENTILATION. 

ments, we must take a different course to that we pur- 
sue with our present system. We must, in the first 
place, become acquainted with the remains which 
have been left to us by time and events, and with the 
assistance of the ancient authors, however incomplete 
their works, the whole will have to be newly con- 
structed. We are bound to inquire first into the 
designation of the restored arrangements, and after 
all the previous labor, it is proper for us to enter 
upon the test to prove the actions which have solely 
occupied our labor by the newer arrangements. But 
the proof cannot be determined there as here in the 
same manner. We cannot by direct experiments 
prove how much fire material was requisite to produce 
certain heat at one of those former buildings, or how 
much the impurities of the air were affected by exhala- 
tion and evaporation, and how much time it required 
to dispense with them in the former arrangement, etc. 
To do this, the former arrangements have to be in 
perfect working order. We have to follow different 
ways ; we have to learn from our own and by other 
experiments the principles most depending upon them, 
and then we have to ask how far the principles have 
been employed by the ancients or not. The compari- 
son between -the old and new methods will then deter- 
mine itself. The remains which will serve as a guide 
may be traced nearly entirely from the Roman baths. 
They are often found, and in great numbers, not alone 
in the warmer parts of Italy, where the heating of the 
private houses is of no conseauence, but likewise 



HEATING AND VENTILATION. 91 

in northern climates, particularly in Germany and 
France. The baths in Pompeii and Herculaneum 
are mostly in their original state. There are also 
remains in Home and in the neighborhood, Sero- 
fano, etc. In general they all exhibit the same ar- 
rangement of a peculiar heating method, but still there 
are in several cases various differences, and those very 
differences will, no doubt, by close investigation, help to 
raise to our conception the acuteness of penetra- 
tion the ancients possessed in such a high degree. No 
doubt the easiest way to arrive at a most correct and 
clear understanding of their arrangements, will be by 
explaining a number of examples. We will commence 
with the winter residence, the villa Tusculana, situa- 
ted on a hill side near Herculaneum, a description of 
which, Winkelman introduces with these words : 
* The wealthier classes of the Romans were better 
provided against cold than we are. Their stoves heat- 
ed the room without molesting the heads of 
the inmates.' The building is low ; underneath 
the earth is a room of the same dimensions as the 
room which is located immediately above it, about two 
feet in height. The lower space or room is named the 
Hypocaustum. In the last named room are small pil- 
lars built of bricks, without mortar, only walled up 
with clay, the better to withstand the heat. Upon 
those pillars bricks are laid, and upon them rests the 
suspended floor. Heating floor called suspensurae 
caldarium (Balinese pensiles). The floor is laid with 
coarse mosaic, the walls of the upper rooms are cov- 



92 HEATING AND VENTILATION. 

ered with different colored marble slabs. In this floor 
are square flues walled in, communicating with the 
Hypocaustum. These flues are built in the surround- 
ing walls, and extend to the upper or second story- 
room, where the heat escaped through lions' heads 
made of terra cotta, and regulated by a plug or stop- 
per. A small passage leads into the Hypocaustum. 
On the other end of the passage is the heating stove 
(Hypocausis praefernium,) from which the heat enters 
through the passage into the Hypocaustum, and from 
thence through the flues, so that the floor became 
heated first, and afterwards the walls. The floor of 
the second story, probably constinicted similarly to the 
first, but perhaps of less thickness, was heated by the 
heat of the room below. Such a general and equal 
diffusion of heat was not accidental, but calculated. 
Therefore Seneca remarks, the lowest and highest 
part receives its heat equally. This mode of heating 
private dwellings is also used for heating baths, pri- 
vate as well as public baths, and the most important 
part of them seems to be the hot room or Caldarium. 
The bath of Buxweiler in Alsace had a somewhat differ- 
ent arrangement to the above. The pillars or piers 
supporting the floor were less in number, but the heat- 
ing flues were not close together as in the former ; on 
the contrary, a space was left between them, which had 
no openings, except in the Hypocausis, and an outlet 
on the end communicating with the open air. Imme- 
diately after the suspended floor became warm, the 
smoke entered the flues and escaped through the 



HEATING AND VENTUATION. 93 

upper outlets. The entrance door was placed imme- 
diately over the fire room, also at a place on the floor 
where the temperature was the highest, so that the 
draft of the air through the opening of the door, was 
at once mixed to an equal temperature. But the flues 
were not always conductors of heat. The pubHc baths 
at Pompeii, for instance, had double walls constructed 
of burnt tiles, set up endways with an open space of 
four inches secured with holdfasts, so that the whole 
room was actually surrounded with a single air volume. 
Is it not plain, that this arrangement proves most 
strikingly that the equal temperature, particularly at 
the floor, was attained in a most excellent manner, but 
it is noticed, there is no preparation made for ventila- 
tion ? But still the arrangement of the Lichtenberger 
bath in Germany, proves that they recognized the 
necessity of introducing fresh air then in the Tepida- 
rium. The mild heated bathing room is entered by a 
canal to supply fresh air, and we shall also find that 
there was care even taken for the escape of impure and 
heated air to a sufficient extent. Both were particu- 
larly requisite in the Caklarium, the heated room. It 
is easily comprehended that in this room fresh air had 
to be introduced most cautiously. A great flow of 
quite cold air, or of air alrogether of low temperature, 
would have acted upon the perspiring multitude not 
alone uncomfortably, but very dangerously. The en- 
tering air had first to be cleared of its^ peculiar and 
off'ensive qualities. It appears this purpose has been 
gained in a most judicious manner, by an arrangement 



94 HEATING AND VEXIXLATION. 

which is illustrated in a picture found in the Lachs 
of Titus. This picture exhibits next to the right two 
fires under two boilers, calculated for water heat. The 
Hypocaustum is divided by three large fire canals, 
placed on a level, calculated to spread under the en- 
tire suspended floor. Between the ceiling of the 
single division of the Hypocaustum and the suspended 
floor three more small fires are placed. Those small 
fire rooms are perhaps nothing more than a continua- 
tion of the three first named larger canals, extending 
to an equal height at the bottom of the larger canals 
for firing purpose ; the fuel is seen burning ; and bend- 
ing over the Hypocaustum, in a right angle around, 
the flames are noticed horizontally between the ceil- 
ing and the suspended floor, in a continued stretch 
forward. The discharge of the horizontal fire chan- 
nels may be traced to the heating flues, probably placed 
in the opposite rear wall, but impossible to be shown 
in the picture. On the left side of the picture, open- 
ings are seen at some distance from the floor ; these 
openings which incline to the ceiling of the Hypocaus- 
tum, entered the room in a downward flow. In the 
ceiling an outlet was prepared, by which the hot air 
had a chance to escape. This arrangement was found 
in a bath house at Serofano, not far from Rome, and it 
seems to be general ; involuntarily those reflections 
call to recollection a former quarrel, which was carried 
on in the past age, with great expenditure of sagacity 
and loss of time over the question, whether the 
Bomans had actually chimney stacks or not. This 



HEATING AND VENTILATION. 95 

quarrel is somewhat amusing. One party was deter- 
mined that 4:he smoke should escape through the 
window openings in the walls, through the roof etc., 
and the other was determined that it should escape 
through the chimney. At the same time both parties 
were a unit that the smoke did neither pass through 
the window nor other wall openings, nor through the 
chimney flues, but through the heating flues. How- 
ever, nobody will lessen the merit this chimney 
quarrel deserves, and it proves how this advanced 
heating method met with a general application wher- 
ever heat was requisite for a continued purpose, and 
by this method only could a perfect result be ex- 
pected." 

COMPARISON OF THE OLD AND MODEliN METHODS. 

" The main difference between the two methods can 
be explained very clearly by simple examples . Take, 
for instance, a stove composed of terra cotta tiles, 
and place a warming spring, a gas or spirit flame, and 
as near the bottom as possible, and near to th6 side 
wall of the same. Then examine the temperature, 
and you will find that the same increases from the 
bottom upwards very rapidly, and that the process of 
heating the bottom and walls is slow, and much 
slower at the bottom. You may feel that the air 
enters at the lower openings very rapidly, and that 
this same air escapes very strongly heated. If the 
warming spring or gas light is w: thdrawn, the former 



96 heaung and ventilation. 

phenomenon diminishes as rapidly as it first appeared. 
By placing a warming spring below the bottom of the 
stove, then the walls will be heated much more than 
before. The bottom receives naturally, not a lower but 
a higher temperature than the other. In the inner 
space the temperature is higher below than above, 
but in a short time the change may be the reverse ; 
the difference, however, between the upper part and 
the lower is small. The air which escapes from the 
chimney flue is by no means as hot, and vehement 
in its movement ; it is on the contrary slow, constant, 
and less heated. As soon as the warming spring is 
removed, then the difference in warmth between the 
upper and lower part returns to its former proportions. 
The constant air draft continues for a considerable 
time, and by degrees works forward. The floor and 
walls have inhaled the warming spring, and changed 
to warming springs themselves, but with a nature not 
allowing the heat to escape rashly, and spouting, but 
sparingly, and in sufficient quantity. The first of the 
two experiments represents the heating method of the 
newer times ; it furnishes the heat especially and 
rashly upwards ; that means, to a place where it is not 
wanted. The last experiment represents the method 
of the Romans. This method furnishes the heat 
especially and quickly into the lower parts of the 
room to be heated, and precisely to the place where 
wanted. Our methods drive a considerable part of 
the heat out of the chimney flue, without any service 
to the chief object. The Romans dispense with the 



HEATING AND VENTILATION. 97 

smoke, but take the advantage of it, and apply its 
heat for heating pnrposes ; the smoke rises between 
the space of a thick outer wall and thin inner waU. 
But the room is heated, not alone by the smoke, but 
also through the heated air of the Hypocaustum ; each 
operates in its individual capacity, and still there is 
heat enough, so as not to disturb the rising power of 
the smoke. Our methods confine the principal bearer; 
the other part of heat, the movable air ; by this means 
it will become as movable as the bearer, and with 
these enters rashly to the upper part of the rooms, 
the inmates below receive the rest, which is impossible 
to place above. 

" The Romans consequently retain this part in the 
lower strata, not trusting to the movable air, but to 
the compactness of the clay. The air is only an inter- 
meddler, the heat is carried to the ceiling, but only to 
the ceiling of the Hypocaustum. The heat is here 
concentrated and supplies the air of the room continu- 
ally, and in such quantity as is requisite for the 
inmates, not more ; and not a particle can escape 
which has not been used. Our methods are calcula- 
ted to supply the floor, with bad warming conductors. 
The Romans construct the floors also not with the very 
best conductors of heat, otherwise they would have 
suffered with too much heat, but nevertheless suffi- 
ciently good without waste of fuel. 

" It is a fact, our methods molest the head with un- 
healthy heat, and leave the feet cold. The ancient 
method warms the feet and leaves the head free. 



98 HEATING AND VENTILATION. 

" Our methods conduct the heat in one air stream of 
small horizontal extent, concentrated to the upper part 
of the room to be heated. Close to the air current the 
occupant finds himself too warm, and the more remote 
he keeps from it the more he feels cold, too cold ! all 
in one and the same room. The ancients knew noth- 
ing of a hot air current ; every where in the occupied 
room, there was an equal and a continued flow of mild 
warm air. It was not possible to find one part of the 
room too hot and the other too cold. Should part of the 
floor near the heating apparatus prove too hot, then it 
follows that the colder air will flow more rapidly. 
The upper rooms of the ancients prove to be as com- 
fortable as the lower ; the upper parts of our theatres 
and concert rooms prove unsupportable for any length 
of time, even with a mechanical ventilation. 

"The air which rises in the flues of the ancient 
arrangement, will furnish heat, and by this process 
will prevent the air rising in the room from returning 
to the floor. Our walls and windows are cold, and lead 
the impure and refrigerant air repeatedly to the lungs 
of the inmates. 

" The temperature of the floor and the walls required 
with the ancients not to be more than the temperature 
requisite for the room, and it necessarily should be so. 
The difference of temperature between the outer air 
and the air in the room could never be so great as the 
rising air near a stove, or from an air-heating appa- 
ratus. So whenever the outer air was introduced, no 
matter in whatever way, owing to the difference in 



HEATING AND VENTILATION. 99 

temperatnre, the inward current of air could never 
enter violently. On the contrary, the colder air was 
forced to descend gently to the floor, receive its warmth 
and then rise again, but not descend a second time, 
not meeting with any cooling process on the walls ; and 
through the outlet flue the warmer and the mixed im- 
purities of the air escape, without being inhaled con- 
tinually. All our new systems of ventilation either 
produced by mechanical power or heat, lead, with few 
exceptions, a strong hot and cold air current into the 
air to be purified, and create a most stirring motion, 
and cause a most complete mixture. Those with heat 
connected systems are calculated for the greatest dif- 
ference in temperature, and carry the supplying good 
air, or so much of it as is not mixed, quickly through 
the outlet flues. The ancients, however, were con- 
tented with a much less difference in temperature, and 
lessened the same accordingly. Mixture was not the 
object, but an equal rising of consumed air current 
through corresponding differences of temperature. 
Not a single violent air current is introduced ; a' great 
number of gentle small rays are spread calmly upon the 
floor, and lift the consumed air equally and continu- 
ally upwards, never to return. A mixture, as formed 
in the other case, is impossible. A colossal air draft 
of 60 metres for each person is not necessary. The 
limit is gained by a minimum. To guard against the 
mechanical action of the strong air rays brought in, 
and also against the action of the higher and lower 
temperature, screens of various forms are introduced, 



100 HEATING AND VENTILATION. 

whicli never answer the purpose fchorougHy ; besides, 
a quantity of air rays introduced presents another dis- 
advantage. It takes too long a time to disseminate, 
and it follows that the current of air in a perfectly clear 
condition, acts only in a confined and local way, and 
never in a general way. The ancients introduce the 
warmer air in fine rays on all sides, and so remove all 
objections. But this gentle withdrawal in this gradual 
manner, has a great advantage over our treatment ; and 
to illustrate it more clearly, some well known facts are 
necessary to be here introduced. Whenever the door 
of a heated room is opened, then the cold air enters at 
the bottom of the opening, but escapes at the upper 
part ; a light will clearly prove this, if applied to the 
opening. Whenever a window is opened, the same 
movement is noticed, no matter how large or small the 
windows may be, or no matter in what position the 
window is placed, at the lower or at the upper part of 
the heated room. The cause of this phenomenon is 
well known : the cold air forces itself in at the lower 
part, ^nd the warmer air must escape at the upper 
part, and the consequence is that the exit of air stops 
at the window at the time an opening is placed above 
the window. The well-known method of ventilation, 
in which a hollow cylinder, divided longitudinally into 
two parts, and placed in the wall or ceiling, rests upon 
the same principle. Now we can form a clear view of 
what is called a voluntary and natural ventilation. 
The numerous pores in the materials are so many ducts 
for the inlet and outlet of air, and the change of air 



HEATING AND VENTILATION. 101 

through those pores takes place as indicated. By duio 
reflection, it is easily seen that the ventilation of the 
ancients conforms to the imitation of the natural ven- 
tilation. When the cooler air enters from a lower 
opening of a flue into a heated room, the warm and 
supplanted air rises in the next higher opening of the 
heated flues, an occurrence which repeats itself 
throughout the room, below and above and on all 
sides. So the impure air travels only one w^ay to the 
outlet, the impure air is not lifted from the floor to the 
ceiling, every sheet of air requires only to rise gradu- 
ally. It is clear that through this process the desired 
result is most surely gained. It is otherwise with our 
newer method, where the air generally enters at the 
lower part and escapes at the upper part, equally so as 
the accumulating impurities move through the whole 
height of the saloon, and where the heated air forms 
its exit through the opening arranged as above, where- 
as the lower impurities, not ascending so high, remain 
behind. The dwelUng rooms and bath rooms of the 
ancients were at an average not so high as ours, and 
it was not necessary they should be. By our methods 
it is important that in the mixture of pure and impure 
air, the pure air should be in a sufficient healthy sur- 
plus. 

" The latger and higher the rooms are, the better. 
The ancients required no such elevation ; on the 
contrary, by the process of lifting the impure air grad- 
ually, the interest of economy was applied, to keep the 
rooms low ; every extension of height requisite for hab- 



102 HEATING AND VENTILATION. 

itable rooms is actually an extravagant consumption, 
requiring more lieat. The heating and ventilation 
conception, however, to which we have accustomed 
ourselves, will naturally restrain us ; but as soon as we 
acknowledge ihe advantage of the arrangements of the 
ancients, with good air equally distributed, then we 
shall require less room for the accumulation of good 
air. The finest mosaic work and ornaments for floors 
and walls of the ancient works, are known. They form 
a contrast to the newer works, and the contrast of the 
practice of using in the one case good and in the other 
bad warming conductors, is in favor of the ancients, 
with a corresponding claim to art also. It is hardly 
possible to suppose that there could be any opposition 
to the hope that theory only has been preached, with- 
out experience . Experience is in advance of theory 
at least two thousand years, and is introduced by 
economical, practical and judicious men, by men every 
way trustworthy. The main object here is only the 
first trial in a time of flourishing science, to form a 
comparison of the results with those of newer methods 
of heating in connection with ventilation. Then when 
this first trial has been made, I think it will be unne- 
cessary to say anything more in its favor ; it will speak 
for itself. All that is left to be done is this, to perfect 
this method by still more experience and through sci- 
ence. 

" Then the combat between ventilation through heat 
or through mechanical power, will subside in itself. 
We have, in this system, economical heating connected 



HEATING AND VENTILATION. 103 

wibli the natural ventilation. Hitherto the trilQing 
effects of the^iatural and voluntary ventilation, through 
the pores of the walls and other accidental openings, 
it was taken for granted could be assisted in two differ- 
ent ways, and so the natural ventilation may be ele- 
vated to its greatest perfection, and if not found suffi- 
cient in all cases, then the mechanical power may as- 
sist, by forcing the pure air perhaps through the same 
air flues, through which the voluntary air may enter. 
There is no comparison more between the two meth- 
ods. It will not be questionable, the one or the oth- 
er, but one alone, or in connection with the other — a 
question which will easily be settled by a strict in- 
quiry into the condition of the air in single rooms." 



CATALOGUE 



OF 



Scientific Books, 



PUBLISHED BY 



D. Van Nostrand, 

23 MURRAY STREET and 27 WARREN STREET, 
PUBLISHER, IMPORTER and BOOKSELLER 




NEW YORKi 

1872 



*^* Copies of this Catalogue, and also Catalogue of Militaiy 
and Naval Books, will be sent post-paid to any address on 



WDlication. 



VALUABLE WORKS 



BRIDGE CONSTRUCTION, 



PUBLISHED BY 



D- Van Nostrand, 

23 Murray Street and 27 Warren Street, N. Y. 



LONG AND SHORT SPAN RAILWAY BRIDGES. By 

John A. Roebling, C. E. Illustrated with 16 large 
finely executed Copper-plate Engravings of Views 
and Plans, together with an Engraved Steel Plate 
of the late John A. Roebling. i vol. imperial folio, 
doth ^ $25 00 

IRON RAILWAY BRIDGE AT aUINCY, ILL. By 

Thomas Curtis Clarke, Chief Engineer. Illustrat d 

with 27 Lithographed Plans, i vol. 4to, cloth 7 50 

IRON TRUSS BRIDGES FOR RAILROADS. Methods 
of Calculating Strains, with a Comparison of the most 
Prominent Truss Bridges, and new Formulas for 
Bridge Computations. By Brevet-Col. Wm. E. Mer- 
rill, Major Corps of Engineers. Illustrated with 9 
Lithographic Colored Diagrams. 4to, cloth 5 00 

KANSAS CITY BRIDGE. With an Account of the Reg- 
imen of the Missouri River, and a Description of the 
Methods used for Foanding in that River. By O. 
Chanute, Chief Engineer, and George Morison, As- 
sistant Engineer. Illustrated by 5 Lithographic 
Views of the Work, and 1 2 Engraved Plans, i vol. 
4to. (In press. ) 



P- VAJI aCSTSANDS PUBllOAXIOHS. 



AJBOT (H, L.) Shgc Artillery in the Campaign against 
Richmond, vlth Notes on the 15-inch Gun, including 
an Algebraic Analysis of the Trajectory of a Shot in its 
ricochet upon smooth water. Illustrated with detailed 
drawings of the U S. and Confederate rifled projectiles. 
By Henry L. Abbot, Maj. of Engineers, and Bvt. Maj.- 
Gencral U. S. Vols., commanding Siege Artillery, 
Armies before Richmond, Paper No. 14, Professional 

Papers, Corps of Engineers, i vol. 8vo, cloth $3 • S<* 

ALEXANDER (J. H.) Universal Dictionary of Weights 
and Measures, Ancient and Modern, reduced to the 
standards of the Jnited States of America. By J. H. 
Alexander. New edition, enlarged. 1 vol. 8vo, cloth. 3.50 
BENE! (S. V.) Electro-Ballistic Machines, and the Schultz 
Chronosccpc. By Brevet Lieut.-Colonel S. V. Benet. 

1 vol. 410, illustrated, cloth 4.00 

BEOOKLYN WATER WORKS. Containing a Descrip- 
tive Account of the Construction of the Works, and 
also Reports on the Brooklyn, Hartford, Belleville, and 
Cambridge Pumping Engines. With illustrations. I 

vol. folio, cloth 15 .00 

BUROH (N. P.) Modern Marine Engineering, applied to 
Paddle and Screw Propulsion. Consisting of 36 colored 
plates, 259 Practical Woodcut Illustrations, and 403 
pages of Descriptive Matter, the whole being an ex- 
position of the present practice of the following firms : 
Messrs. J. Penn & Sons ; Messrs. Maudslay, Sons & 
Field; Messrs. James Watt & Co.; Messrs. J. & G. 
Rennie ; Messrs. R. Napier & Sons ; Messrs. J. & W. 
Dudgeon ; Messrs. Ravenhill & Hodgson ; Messrs. 
Humphreys & Tenant ; Mr. J. T. Spencer, and Messrs. 
Forrester & Co. By N. P. Burgh, Engineer. In 1 thick 

ToL 4to, cloth • • • • • 25 .00 

Do. do. half morocco. ••••.•••,•.••••••••• 30.00 



D. VAlf NOST^AND'S PUBI^0ATIO»& 

CAMPIN on the Construction of Iron Roofs. By Francis 

Campin. 8vo, with plates, cloth $3 'OO 

CHAUVENET (Prof. Wm.) New Method of Correcting 
Lunar Distances, and Improved Method of Finding thr 
Error and Rate of a Chronometer, by equal altitudes. 

By Wm. Chauvenet, LL. D. i vol. 8vo, cloth 3.00 

COLBURN. The Gas Works of London. By Zerah Col- 
burn, C. E. 1 vol. i2mo, boards 75 

CRAIO (B. F.) Weights and Measures. An Account of 
the Decimal System, with Tables of Conversion for 
Commercial and Scientific Uses. By B, F. Craig, M. 

D. 1 vol. square 32mo, limp cloth SO 

COFFIN. Navigation and Nautical Astronomy; pre- 
pared for the use of the U. S. Naval Academy. By 
Prof. J. H. 0. Coffin. 4th edition enlarged. i2mo, 

cloth. 3.50 

OBIHTER (M. L.) On the Manufacture of Steel. Trans- 
lated from the French. By Lenox Smith. With an 
Appendix on the Bessemer Process in the United 
States, by the Translator. Illustrated by several En- 
gravings. In press 

SAELTZER- A Treatise on Acoustics, in Connection 
with Ventilation. By Alexander Saeltzer. 12 mo. 
In press 

VBANCIS. Lowell Hydraulic Experiments, being a selec- 
tion from Experiments on Hydraulic Motors, on the 
Flow of Water over Wiers, in Open Canals of Uniform 
Rectangular Section, and through submerged Orifices 
and diverging Tubes. Made at Lowell, Massachusetts. 
By James B. Francis, C. E. 3d edition, revised and 
enlarged, with many new experiments, and illustrated 
with twenty-three copperplate engravings, i voL 410, 

cloth./ U.M 

4 



D. VIM NOSTRA m>« PUBLIOATIONB, 

FBANCIS. On the Strength of Cast-iron Pillars,with Tables 
for the use of Engineers, Architects, and Builders. By 
James B. Francis, Civil Engineer, i vol. 8vo, cloth. • $2.oa 
«A scientific treatise of inestimable value to those for whom it is intended.''— ^Mton 

Daily Advertiser, 

QILLMOEE (Gen. Q^A.) Treatise on Limes, Hydraulic 
Cements, and Mortars. Papers on Practical Engineer- 
ing, U. S. Engineer Department, No. 9^ containing 
Reports of numerous Experiments conducted in New 
York City, during the years 1858 to 186 1, inclusive. 
By Q^ A. Gillmore, Bvt. Maj.-Gen , U. S. A., Major, 
Corps U. S. Engineers. With numerous illustrations. 
» vol. 8vo, cloth 4.O0» 

GOUGE. New System of Ventilation, which has been 
thoroughly tested^nder the patronage of many dis- 
tinguished persons,^ By Henry A. Gouge. Third 
edition, enlarged^ With many illustrations. 8vo, 

cloth 3 .00 

HARRISON. The Mechanics' Tool Book, with Practical 
Rules and Suggestions for Use of Machinists, Iron 
Workers, and others. By W. B. Harrison, associate 
editor of the " American Artisan.** Illustrated with 44 
engravings. 1 2mo, cloth 2*50 

HENRICI (Olaus). Skeleton Structures, especially in their 
application to the Building of Steel and Iron Bridges. 
By Olaus Henrici. With folding plates and diagram!. 
I vol. 8 vo, cloth 3 . 00 

HEWSON (Wm.) Principles and Practice of Embanking 
Lands from River Floods, as applied to the Levees of 
the Mississippi. By William Hewson, Civil Engineer. 
1 vol. 8vo, cloth 2 .00 

** This is a valuable treatise on the principles and practice of embankin^^nds from 
riT«r floods, as applied to Leyecs of the Mississippi, by a highlj intelligent and experi- 
enced engineer. The anther says it is a first attempt to reduce to order and to rule ihf 
design, execution, and measurement of the Levees of the Mississippi. It is a most uMfte 
«Bd B«eded ooatribntion to asJentific literature).**— F\i7«ddpJkia EtaeifiimQ JoutmdL, 



D. VAN IJOSTKAND'S PUBULGATIONS. 



EOLLET (A. L.) Railway Practice. American And Euro- 
pean Railway Practice, in the economical Generation of 
Steam, including the Materials and Construction of Coal- 
burning Boilers, Combustion, the Variable Blast, Va- 
porization, Circulation, Superheating, Supplying and 
Heating Feed-water, &c., and the Adaptation of Wood 
and Coke-burning Engines to Coal-burning; and in 
Permanent Way, including Road-bed, Sleepers, Rails, 
Joint-fastenings, Street Railways, &c., &c. By Alex- 
ander L. Holley, B. P. With 77 lithographed plates. 
1 vol. folio, cloth , •$i2,oe 

• • • <»A11 these subjects are treated by the author in both an intelligent and Intel 
ligible manner. The facts and ideas are well arranged, and presented in a clear and sim- 
ple style, accompanied by beautiful engravings, and we presume the work will be 1^ 
garded as indispensable by all who are interested in a knowledge of the construction d 
railroads and rolling stock, or the working o£ locomotives. "—.Slnen^t/lc American, 

HUNT (R. M.) Designs for the Gateways of the Southern 
Entrances to the Central Park, By Richard M. Hunt. 
With a description of the designs. I vol. 4to, illus- 
trated, cloth 5 00 

KING (W. H.) Lessons and Practical Notes on Steam, 
the Steam Engine, Propellers, &c., &c., for Young Ma- 
rine Engineers, Students, and others. By the late W. 
H. King, U. S. Navy. Revised by Chief Engineer J. 
W. King, U. S. Navy, Twelfth edition, enlarged. 8vo, 

cloth ^ 2.0C 

THE KANSAS CITY BRIDGE, with an account of the 
Regimen of the Missouri River, and a description of 
Methods used for founding in that River. By O. 
Chanute, Chief Engineer, and George Morrison, 
Assistant Engineer. Illustrated with five lithographic 
views and twelve plates of plans. 4to, cloth 6 . 00 

KeCOBMICE (R. C). Arizona : Its Resources and Pros- 
pects. By Hon. R. C. McCormick. With map, 8vo, 
paper '5 



D. TAN lfOSTSAND*B PTTBUCATIONfl. 



MIKIPIE (Vm.) Mechanical Drawing. A Text-Book 
of Geometrical Drawing for the use of Mechanics and 
Schools, in which the Definitions and Rules of Geometry 
arc familiarly explained ; the Practical Problems arc ar- 
ranged, from the most simple to the more complex, and 
in their description technicalities are avoided as much 
as possible* With illustrations for Drawing Plans, Sec- 
tions, and Elevations of Buildings and Machinery ; an 
Introduction to Isometrical Drawing, and an Essay on 
Linear Perspective and Shadows. Illustrated with over 
200 diagrams engraved on steel. By Wm. Minifie, 
Architect. Seventh Edition. With an Appendix on 
the Theory and Application of Colors. 1 vol. 8vo, 
cloth $4 00 

WILLIAMSON. Practical Tables in Meteorology and 
Hypsometry, in connection with the use of the 
Barometer. By Col. R. S. Williamson, U. S. A. 
I vol. 4to, flexible cloth 2 . 50 

CULLEY. A Hand-Book of Practical Telegraphy. By 
R. S. Culley, Engineer to the Electric and Interna- 
tional Telegraph Company. Fourth edition, revised 
and enlarged. 8vo. Illustrated. Cloth 5 .00 

POPE. Modern Practice of the Electric Telegraph. For 
Electricians and Operators. By Frank L. Pope. 
Fourth edition, revised and illustrated. 8vo, cloth. . 2.0a 

MINIFIE (Wm.) Geometrical Drawing. Abridged from 
the Octavo edition, for the use of Schools. Illustrated 
with 48 steel plates. Fifth edition, i vol. i2mo, 
cloth 2 . 00 

** It is well adapted as a text-book of drawing to be nied in oar High Schools and 
icademies where this useful branch of the fine arts has been hitherto too much net* 
loctod.* *—>Au{on JaumdL 

7 



D. TAN NOSI^AND's PUBULCATI058. 

PIERCE (Prof. Benj.) System of Analytical Mcchanio. 
Physical and Celestial Mechanics, by Benjamin Pierce, 
Perkins Professor of Astronomy and Mathematics in 
Harvard University, and Consulting Astronomer of the 
American Ephemeris and Nautical Almanac. Developed 
in four systems of Analytical Mechanics, Celestial Me- 
chanics, Potential Physics, ai\d Analytic Morphology. 
1 vol. 4to, cloth $10.00 

••I have re-exarained the memoirs of the great geometers, and have striven to oonsoli. 
date their latest researches and their most exalted forms of thought into a consistent an4 
uniform tceatise. If I have hereby succeeded in opening to the students of my country « 
readier access to these choice jewels of intellect; if their brilliancy is not impaired in thii 
attempt to reset them; if, in their own constellation, they illustrate each other, and con- 
eentrate a stronger light upon the names of their discoverers; and, still more, if any gem 
which I may have presumed to add is not wholly lustreless in the coJection, — ^! euadl feel 
mat my work bas not been in vain."— .Kcirarf/rom the Preface, 

PLYMPTON. The Blow-Pipe ; a System of Instruction in 
its Practical Use, being a Graduated Course of Analy- 
sis for the Use of Students and all those engaged in the 
Examination of Metallic Combinations. Second edi- 
tion, with an appendix and a copious index. By Geo. 
W. Plympton, of the Polytechnic Institute, Brooklyn. 
' 1 vol. 1 2mo, cloth 2 .oo 

POOE (S. M.) Method of Comparing the Lines and 
Draughting Vessels Propelled by Sail or Steam. In- 
cluding a chapter on Laying off on the Mould-Loft 
Floor. By Samuel M. Pook, Naval Constructor. I 
vol. 8vo, with illustrations, cloth 5.00 

RANDALL'S QUARTZ OPERATOR'S HAND-BOOK. By 

P. M. Randall. New edition, revised and enlarged. 
Fully illustrated. i2mo, cloth 2 00 

ROGERS (H. D.) Geology of Pennsylvania. A complete 
Scientific Treatise on the Coal Formations. By Henry 
D. Rogers, Geologist. 3 vols. 4to, plates and maps. 

Boards • ••• »• 30.00 

8 



D. TAK N0STX\A1ID S PXTBUOATIONS. 



SUBHAHIBTE BLASTING IN BOSTON HABBOB^ 
MASSACHUSETTS. Removal of Tower and Cor- 
win Rocks. By John G. Foster, Lieutenant-Colonel 
of Engineers, and Brevet Major-General, United 
States Army. With illustrations. 4to, cloth $3 50 

8HAFFNER (T. P.) Telegraph Manual. A complete 
History and Descripfion of the Semaphoric, Electric, 
and Magnetic Telegraphs of Europe, Asia, and Africa, 
with 625 illustrations. By Tal. P. ShafFner, of Ken- 
tucky. New edition. 1 vol. 8vo, cloth, 850 pp.... 6.50 

SILVERSMITH (Julius). A Practical Hand-Book for Mi- 
ner&, Metallurgists, and Assayers, comprising the most 
recent improvements in the disintegration, amalgama 
tion, smelting, and parting of the Precious Ores, with a 
Comprehensive Digest of the Mining Laws. GreatU 
augumented, revised, and corrected. By Julius Silver- 
smith. Fourth edition. Profusely illustrated, i vol. 
1 2mo, cloth 3 • GO 

SIMM'S LEVELLING. A Treatise on the Principles and 
Practice of Levelling, showing its application to pur- 
poses of Railway Engineering and the Construction 
of Roads, &c. By Frederick W. Simms, C. E. 
From the fifth London edition, revised and corrected, 
with the addition of Mr. Law's Practical Examples 
for Setting Out Railway Curves. Illustrated with 
three lithographic plates and numerous wood-cuts. 
8vo, cloth 1 . 50 

SUBMARINE WARFARE, Oifensive and Defensive, 
including a Discussion of the Offensive Torpedo 
System. By Lieut -Commander J. S. Barnes, U.S.N, 
With illustrations. 8vo, cloth 5 .00 



D. VAN NOSTRANDS PUBLICATIONS. 

PLATTNER'S BLOW-PIPE ANALYSIS. A Complete 
Guide to Qualitative and Quantitative Examinations 
with the Blow-Pipe. Revised and enlarged by Prof. 
Richter, Freiberg. Translated from the latest Ger- 
man edition by Henry B. Cornwall, A. M., E. M 
8vo, cloth $7- 5<5 

SPHERICAL ASTRONOMY. By F. Brunnow, Ph. Dr. 
Translated by the Author from the Second German 
edition. I vol. Svo, cloth 6 • 50 

STILLMAN (Paul). Steam Engine Indicator, and the Im- 
proved Manometer Steam and Vacuum Gauges — their 
Utility and Application. By Paul Stillman. New 
edition, i vol. i2mo, flexible cloth. 1 .oo 

*<The purpose of this oseflil yolume is to bring to the notice of the namerooa class of 
those interested in the bnilding and the use of steam engines, the economy and safety Attend* 
fng the use of the instrument therein described, llie Manometer has been long used— the 
Inventor is Watt in a cruder form; and the forms herein described are patented by the 
author. The language of the author, the diagrams, and the scientific mode of treatment^ 
recommend the book to the careful consideration of all who have engines in their care,'' — 
BottonPost. 

SWEET (8. H.) Special Report on Coal ; showing its Dis- 
tribution, Classification, and cost delivered over different 
routes to various points in the State of New York, and 
the principal cities on the Atlantic Coast, By S. H. 
Sweet. With maps, 1 vol. 8 vo, cloth 3 . 00 

WILLIAMSON. Practical Tables in Meteorology and 
Hypsometiy, in connection with the use of the 
Barometer. By Col. R. S. Williamson, U. 8. Army. 
4to, flexible cloth 2 . 50 

WALKER (W. H.) Screw Propulsion. Notes on Screw 

Propulsion, its Rise and History. By Capt. W. H. 

Walker, U. 8. Navy. 1 vol. 8vo, cloth 75 

"After thoroughly demonstrating the efficiency of the screw, Mr. Walker proceeds to 
point out the yarious other points to be attended to in order to secure an efficient man-ot- 
irar, and eulogizes throughout the readiness of the British Admiralty to test every nov- 
elty calculated to give satisfactory results. • • ♦ • Commander Walker^s book oon* 
lains an immense amount of concise practical data, and every item of information r^ 
•orded fully proves that the various points bearing npon it have been weU oonaidf'tid 
liwtoasly to expressing an opinion.'*— >£oiidon Mining JowmdL 

10 



D. VAN NOSTBAND*S PUBLICATIONS. 



WEISBACH'S MECHANICS. New and revised edition. 
A Manual of the Mechanics of Engineering, and of 
the Construction of Machines. By Julius Weisbarh, 
Ph. D. Translated from the fourth augmented and 
improved German edition, by Eckley B. Coxe, A. M., 
Mining Engineer. Vol. I. — Theoretical Mechanics. 
I vol. 8vo, I, I GO pages, and 902 wood-cut illustra- 
tions, printed from electrotype copies of those of the 

best German edition $10.00 

Abstract of Contents. — Introduction to the Cal- 
culus — The General Principles of Mechanics — Pho- 
ronomics, or the Purely Mathematical Theory of 
Motion — Statics of Rigid Bodies — The Application 
of Statics to Elasticity and Strength — Dynamics of 
Rigid Bodies — Statics of Fluids — Dynamics of Fluids 
— ^The Theory of Oscillation, etc. 

« The present edition is an entirely new work, greatly extended and very much im« 
IH'Oved. It forms a text-book which must find its way into the hands, not only of eTery 
student, but of every engineer who desires to refresh his memory or acquire clear ideas 
on doubtful points." — The TechnologisU 

WAED (J. H.) Steam for the Million. A popular Trea- 
tise on Steam and its Application to the useful Arts, 
especially to Navigation. By J. H. Ward, Com- 
mander U. S. Navy. New and revised edition, i 
vol. 8vo, cloth 1 . 00 

WHILDEN (J. K.) On the Strength of Materials used 
m Engineering Construction. By J. K. Whilden. 
I vol. i2mo, cloth 3 ,00 

WILLIAMSON (R. S.) On the use of the Barometer on 
' Surveys and Reconnaissances. Part I. Meteorology 
in its Connection with Hypsometry. Part II. Ba- 
rometric Hypsometry. By R. S. Williamson, Bvt. 
Lieut. -Col. U. S. A., Major Corps of Engineers. 
With Illustrative Tables and Engravings. Paper 
No. 15, Professional Papers, Corps of Engineers. 

I vol. 4to, cloth ^ , 15 00 

11 



D. VAN NOSTRANDS PUBLICATIOIIS. 



BOEBimG (J. A.) Long and Short Span Railway 
Bridges. By John A. Roebling, C. E. Illustrated 
with large copperplate engravings of plans and views. 
Imperial folio, cloth • . . $2 5 . co 

CLARKE (T. C.) Description of the Iron Railway 
Bridge over the Mississippi River, at Quinqy, Illi- 
nois. By Thomas Curtis Clarke, Chief Engineer. 
Illustrated with 27 lithographed plans, i vol. 8vo, 
cloth. 7 50 

TUNNER (P.) A Treatise on Roll-Turning for the 
manufacture of Iron. By Peter Tunner. Trans- 
lated and adapted by John B. Pearse, of the Penn- 
sylvania Steel Works, with numerous engravings 
and wood-cuts, i vol. 8vo, text, and fol. vol. Plates, 
cloth 10.00 

ISHEEWOOD (B. F.) Engineering Precedents for Steam 
Machinery. Arranged in the most practical and 
useful manner for Engineers. By B. F. Isher- 
wood, Civil Engineer, U. S. Navy. With illustra- 
tions. Two volumes in one. 8vo, cloth a . 5c 

JAUERMAN. Treatise on the Metallurgy of Iron, con- 
taining outlines of the History of Iron Manufacture, 
methods of Assay, and analysis of Iron Ores, pro- 
cesses of manufacture of Iron and Steel, etc., etc. 
By H. Bauerman. First American edition. Re- 
vised and enlarged, with an appendix on the Martin 
Process for making Steel, from the report of Abram 
S. Hewitt Illustrated with numerous wood engra- 
vings. 1 2mo, cloth 2 . 50 

"This is an important addition to the stock of technical works published in thii 
country. It embodies the latest facts, discoveries, and processes connected with tlM 
inanufacture of iron and steel, and should be in the hands of every person interested la 
the subject, as well as in all technical and scientific libraries." — Sdentijvc Americati, 

PEET. Manual of Inorganic Chemistry for Students. 
By the late Dudley Peet, M. D. Revised and cn«# 
Urged by Isaac Lewis Peet, A. M. iSiao, cloth. . . 75 

12 



D. TAU NOSTBAND'8 PUBLICATIONS. 



HUQENT. Treatise on Optics : or, Light and Sight, the- 
oretically and practically treated ; with the applica- 
tion to Fine Art and Industrial Pursuits. By E. 
Nugent. With one hundred and three illustrations. 
i2mo, cloth $2.00 

*♦ nits book is of a practical rather than a theoretical kind, and is designed to aflTord 
iccuraio and complete information to all interested in applications of the science.— iStmnd 
IhbU. 

SABINE. HISTORY AND PROGRESS OF THE ELEC- 
TRIG TELEGRAPH. By Robert Sabine, C.E. 2d 
edition, with additions. Fully illustrated. i2mo, do. 1.75 

GLYNN (J. ) Treatise on the Power of Water, as applied 
to drive Flour Mills, and to give motion to Tur- 
bines and other Hydrostatic Engines. By Joseph 
Glynn. Third edition, revised and enlarged, with 
numerous illustrations. 1 2mo, cloth 1.25 

PRIME. TREATISE ON ORE DEPOSITS. By Bern- 
hard Von Cotta. Translated from the Second Ger- 
man edition by Frederick Prime, Jr., Mining Engi- 
neer, and revised by the Author. With numerous 
illustrations. 8vo, cloth 4 .00 

HDMBER. A Handy Book for the Calculation of Strains 
in Girders and similar Structures, and their Strength, 
consisting of Formulae and corresponding Diagrams, 
with numerous details for practical application. By 
William Humber. i2mo, fully illustrated, cloth. . • 2.5^ 

GILLMORE. Engineer and Artillery Operations against 
Charleston, 1863. By Major-General Q. A. Gill- 
more. With 76 lithographic plates. 8vo, cloth ... 10.00 

■' Supplementar)' Report to the above, with 7 litho- 

fraphed maps and views. 8vo, cloth 5 .Ott 

13 



D. VAN Nl/STRAND'S PUBLICATIONS 

AUCHINCLOSS. Link and Valve Motions Simplified. 
Illustrated with 2>1 wood cuts, and 21 lithographic 
plates, together with a Travel Scale, and numerous 
useful Tables. By W. S. Auchincloss. 8vo., cloth, I3 oc 

JOYNSON. HETAIS USED IN CONSTRUCTION- 

Iron, Slecl, Bessemer Metal, etc., etc. With illus- 
trations. 1 2mo, cloth 75 

THE ART OF GRAINING. How Acquired and How 
Produced. By Pickert and Metcalf. Beautifully 
Illustrated, tinted paper. 8vo. In press 

VAN BUREN. Investigations of Formulas, for the strength 
of the Iron parts of Steam Machinery. By J. D. Van* 
Buren, Jr., C. E. Illustrated, 8vo., cloth, 2 00 

JOYNSON. Designing and Construction of Machine 

Gearing. Illustrated, 8vo., cloth, J 00 

COIGNET-RETON. and other Artificial Stone. By Q. A. 

Gillmore. Illustrated with 9 Plates. 8vo, cloth 2. 50* 

FREE HAND DRAWING, a Guide to Ornamemal, Fig- 
ure and Landscape Drawing. By an Art Student. 
Profusely illustrated, 18 mo., cloth, 75 

THE EARTH'S CRUST. A handy Outlme of Geology. 

By Dav^'d Page. Illustrated, i8mo., cloth, 75 

DICTIONARY of Manufactures, Mining, Machinery, and 
the Industrial Arts. By George Dodd. i3mo., 
cloth, 2 oc 



D. TAN MOSTBAND'S PUBLICATIOXSi 



MATER. Lecture Notes on Physics. By Alfred M. 

Mayer, Ph. D. 8vo, cloth $1.00 

A TREATISE ON THE RICHARDS STEAM-ENGINE 
INDICATOR, with Directions for its Use. By Chas. 
T. Porter. Revised with notes and large additions, 
as developed by American Practice, with an Appendix 
containing useful formulae and rules for Engineers. 
By F. W. Bacon, M. E., Member of the American 
Society of Civil Engineers. i8mo, illustrated. Cloth, i.oo 

ON THE FILTRATION OP RIVER WATERS, for the 

Supply of Cities, as practised in Europe, made to the 
Board of Water Commissioners of the City of St. 
Louis. By J. P. Kirkwood, Civil Engineer. Illus- 
trated by 30 engravings. 4to, cloth 15.00 

THE PLANE-TABLE AND ITS USE IN TOPOGRAPH- 
ICAL SURVEYING. From the Papers of the U. 
S. Coast Survey. 8vo, illustrated. Cloth 2 . 00 

REPORT on Machinery and Processes of the Industrial 
Arts and Apparatus of the Exact Sciences. By F. A. 
P. Barnard, LL. D. Paris Universal Exposition, 
1867. I vol. Svo, cloth 5 .00 

IRON TRUSS BRIDGES FOR RAILROADS. The 

Method of Calculating Strains in Trusses, with a 
♦Careful Comparison of the most Prominent Trusses in 
Reference to Economy in Combination, etc. By 
Brevet Colonel William E. Merrill, U. S. A. Illus- 
trated. 4to, cloth 5 .00 

DSEFUL INFORMATION FOR RAILWAY MEN. 
By W. G. Hamilton, Engineer. Fourth edition, re- 
vised and enlarged. 600 pp. ^Morocco gilt. For 

potkei J ,oj^ 

1.^ 



Van Nostrand's 

eclectic 
Engineering Magazine. 



t»f 



€€ 



112 Pages, large 8vo, Monthlt. 

First Number was Issued Jan. i, 1869 

Illustrated. 

PRICE $s A YEAR IN ADVANCE. SINGLE COPIES 50 CTS. 

Vol. I. January to December, 1869. Cloth $5 .00 

2. " " June, 1870. " ......... 3.C50 

3. July to December, 1870. ** 3.00 

" 4. January to June, 1871. *' 3.0c 

" 5- July to December, 1871. " 3-00 

VAN NOSTRAND'S MAGAZINE consists of Articles Se- 
lected and Matter Condensed from all the Engineering Serial 
Publications of Europe and America, together with Original 
Articles. 

Few active engineers 01 artisans can take all or most of the 
professional newspapers ; none can afford the time to wade 
through the columns of the whole scientific press to get at the 
really important news, information, and opinions. 

The object of this Magazine is to present within limits of space 
and cost that all can afford, the cream of not less than fifty engi 
neering, mechanical, chemical, and metallurgical publications. 
The French and German Magazines will be largely translated. 
Papers and discussions before Societies will be condensed. 
Professional news from all sources will be compiled at length. 

16 






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